Well I'll say one thing about communicating online, at least when it's a post that you can take your time writing: it'd never happen with some people when you talk in person just because they probably wouldn't shut up long enough, and some people like me are probably too polite to interfere if someone just has to yak away. The whole classic bulletin board format is asychronous in time, which is convenient because you can just get to it when you have the time, but these days everyone has to be connected all the time.
The information we don't have online in terms of tone of voice, body language and so forth does cut both ways - it can give us a better sense of what someone is trying to communicate, but it can also make us a bit self conscious (which is also the case to some degree even if they're on a webcam) and as a result possibly put on a facade rather than be ourselves. Lets face it, people do judge other people based on superficial things, and traditionally online communication is potentially a way to relate based on the merit of what someone actually says without the typical prejudices that is neither here nor there. Of course, it is also possible to project a certain image online too, but that has to do with the individual more than the content that's communicated.
So that only makes sense if you're actually interested in an exchange of ideas, some people really just want to be social and talking about anything in depth doesn't seem to be their cup of tea, or maybe being social is as important to them as the sharing of ideas. A lot will depend on what you use it for and how you use it. The internet does have some bias in itself but most people will never even identify any of them, in which case we can't really talk intelligently about it even if our experience is that it is limiting. There are many different types of sites and different ways to use them, if we have some awareness of how they're set up then we'll be in a better position to use it more intelligently.