There are many types of blogs out there and I read a fair variety of them. One type is an "information aggregate" which collects news and information from sites of interest to its readers and presents it in smaller bites with a link back to the original posts or articles.
Virtually all of the Gawker Media sites are such places which collect news gathered by others or form content based on user input and then offer up samples or opinions based on that news. Very little of its content tends to be original pieces researched, written or extrapolated from its writers' personal experiences, though at least some of it is. One of the best and most useful sites on the web, Lifehacker, is a part of Gawker's suite of sites. Lifehacker's editors and writers keep an eye on what is new and useful and distill that information for us so we don't have to follow things like when Google changes gmail or find useful articles that help us live a greener, cheaper life.
While I believe that a lot of information aggregate sites perform very useful services to readers and drive traffic to the sites which they cull information from, I have concerns about what they represent and the trends that spawn as a result of their form of presenting content. At their best, such sites provide such a small thumbnail of the content of the sites they poach from that interested readers have no choice but to visit the site the information originated from to get more information. At their worst, they steal so much that there is no need to click through to the parent article and give the people who worked hard to create the original content their readership.
The point at which a site which recruits editors to spend their days gleaning "news" from other sources treads over the line from promoting those sites to stealing their intellectual property can be a tricky one. How much parroting of content can one do before they've reduced the chances that the reader will feel the need to move on to the original source? Additionally, there are issues of profiting from the work of others at play. If the New York Times writes an article and parts of that article are featured on an aggregate site, does that site have the right to profit from what it has gleaned from the New York Times when the Times never agreed to allow any part of their article on that site?
This very issue is currently being dealt with on the Apartment Therapy web site as the New York Times has asked them to remove all posts related to Times articles. Like Gawker, Apartment Therapy is host to a suite of sites and derives most of its content from users and searching for articles and other posts related to their core content (interior design and home life). Unlike Gawker Media's sites, they tend to show more of the original source articles and write less involved editorials or opinion pieces to accompany the information they reproduce.
The comments section about the article linked in the previous paragraph is full of people talking about both sides (including myself). Personally, this entire situation is a kissing cousin of an issue which has aggrieved me for quite some time and that is bloggers who create nothing unique, but ride on the coattails of those who do. In the case of aggregators, they do this for profit. In their defense, many of them are performing a valuable service and are helping out the sites who they showcase. Without a doubt, any site featured on sites like Gawker's are going to see a huge (almost certainly welcome) upsurge in traffic.
In the case of individual bloggers, most of them do it for ego-driven reasons. They want attention and they either have nothing in their lives which they feel is worth writing about, or they are too paranoid about privacy to expose their lives for the sake of receiving the desired attention. They mine other people's sites for content to piggyback off of, more often than not doing so by picking up on an issue someone else has spoken about and pontificating on why they are wrong.
The bottom line is that much of the blogging world is like a parasite to true journalists. However, I must hasten to point out that sometimes the blogging world is represented by people who are actually amateur journalists themselves. For the sake of clarity, I will say that I call anyone a "journalist" who writes uniquely about something rather than using someone else's work in whole or in part or as a springboard for a counterpoint piece. (And, incidentally, I'd be more impressed with people who wrote counterpoint pieces if they spent more time making their own points rather than reading something else and then and only then finding something to say.)
The parasitical nature of a lot of blogging doesn't have to be a harmful one. Sometimes the "parasite" assists the host, as it were. However, by and large, I think that is not the case. Those who create unique content invest a huge amount of time or money (or both) in their work and the fruits of their labor are regarded as an information larder for anyone to raid because of claims of "fair use". The problem is that the liberal sampling of professional journalistic sources by bloggers and aggregators undermines the need of readers to seek out the sites which created that information on a regular basis. In essence, if I know I can rely on a site like Apartment Therapy to point out any lifestyle article in the New York Times which concerns topics like design, home organization or cooking, I have little incentive to visit the Times site regularly and skin through their entire list of articles. This in turn reduces the chances that I'll become a regular reader. Apartment Therapy could be siphoning off readership by being too reliable a source of information on articles of interest.
Additionally, while I think aggregators and even private bloggers sometimes do a great job of finding far flung sites and bringing them to the attention of readers, many of them rely far too much on external sources rather than developing their own content. Aggregators do this because it is far cheaper to hire editors to scour the web than writers to create unique pieces. Bloggers do it because their lives are tedious and its hard to find something interesting in their own experience to write about on a regular basis.
While aggregators claim that they want to help the sites they point to, the real reason they showcase the web sites of others is that the more new posts you put up, the more page views you get and the more ad revenue you generate. Using more unique but high quality content is less profitable than semi-regurgitation of the existing content created by external sources.
The bottom line is that those who use the content of others to fuel their blogs are serving to remove the profit from and incentive to create unique content from the sources they mine. At the end of the line if such a trend continues is a diminishing pool of original writers, journalists, and reporters as it becomes increasingly more difficult to make money from your hard work. While aggregators and content poachers are likely indifferent to the harm they do as long as they gain more profit by their efforts, they are essentially contributing to the demise of the sources from which they derive most of their content.