I think though, the posting of links is to attempt to give some credence to what one is saying- it's all well and good for me to say "Cheney supports torture" but if I can't back it up with facts, it's just me yammering, much like right-wingers who scream about Hillary being a lesbian (how someone's sexual preferences, true or not, became a criticism of character, I don't know, but they sure like to throw that rumor around a lot without any backup). Admittedly, I don't see the point in posting someone else's commentary, unless it says something funnier or more eloquently than I can (and lots of people say lots of things funnier or more eloquently than I can; it's why those people get paid to do it).
I like to read most of the links posted, though, and I think it's worth taking a look at opposing views, because many times, if the writer is any good, he or she will have some points to make. And if I disagree with the viewpoint, I need to be able to articulate why (a good example is the article condemning the HPV vaccine that Timm posted a while back- read the article thoroughly and it was clear it was playing fast and loose with the facts, but I had to read it through a few times to figure out what was not ringing true, and that improved my critical thinking skills, so thanks for that, Timm. Seriously.
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What I find irritating, honestly, is people attacking someone's points without reading the links the person has posted to support them. It's like they're so terrified they'll find something to change their minds they won't look at it. Read the link. Or don't comment on it. Whatever. Not so hard. Lord knows I'm not perfect in that respect myself, but at least I try.