Yeah, I completely agree with Graeme. When you talk with someone face-to-face, you can see their body language, tone and so one and understand better what they're saying.
Most probably yes! I mean, with the advantage of anonymity, you tend to defend your causes (sexuality, colour...) more fiercely. Like if someone from internet starts raving about gays being abomination blah blah blah, I will surely give him my piece of thoughts and where he can shove his opinions. But had it been someone face-to-face, I wouldn't have been brave enough to do it, perhaps even if I was out.
But is this a communication problem? I don't think so.
Talking about "definition of a key term", it's definitely more probable to occur online coz not all of us has a deep knowledge of the language. In US, Uk, Australia, you guys talk and live in English but guys like me don't. English is a learnt subject. Not everyone here would be able to converse fluently in English! When chatting ore exchaging views online, small misunderstandings are bound to occur, especially if defending oneself.
Ieshwar