While internet takes down the barriers in one sense, I find communication in writing to be lacking. Typing out different explanations to explain something as abstract as feeling and be completely understood is difficult. Who wants to be frustrated by the necessity of re-explaining what they think they have already expressed so well? Who wants to be the one constantly saying lolwut all the time and feeling like a jackass?
Tone in speech is a great indicator of what someone really means as is facial expression and body language. All these non-verbal cues are lacking online. And while misunderstandings can be more easily avoided with direct, clear phrasing, some people prefer abstractions, or lack the ability to word their posts in any semblance of linear thought. Most of the negative drama created is caused by communication fuck-ups. That shit hurts people. I really don't want to laugh at something, thinking it was a joke, and then find out the person was totally serious. Done it a lot already, and I wish I could take it back.
So I admit that some of what I perceive as a barrier is self-imposed, and thus not necessarily 'real', but still a compelling reason for me.