Expression through the text medium is totally different to the world of vocal interaction. The reason is because very often in situations such as at work, people don't want to really talk unless its about the work, then there are the cliques who have that arrogance and know all the inside jokes, for whatever reason, maybe they are on the same radar. who knows.
I see what you are saying though, it is true to some extent but interaction in the physical life is instant, you have Zero time to really think over what you want to say, so the extroverts are far more suited to group interaction and the like. Believe it or not but many people make judgements on physical looks superficially through perception as well. This is not an issue for people online.
For me I am only comfortable on my own which is a catch-22 because it means i recite my favourite movie lines and jokes but i dont get to share it with anyone. Or I can be functional socially (sort of) if i have had a few drinks. Which to me personally is giganticly dissapointing.
I know that if i find the right environment for me then i can become more comfortable to communicate more, but out of 5 jobs, 3 educational facilities, parties that i have attended in the past, i realise that finding that comfortable environment for me is not easy.
The only time i felt comfortable and relaxed in a group is when i was working on a university project with people who were mostly nerdy and awkward, i also felt that there was no real presence of ego or intimidation or authority, my true RELAXED personality showed up then. This to me proves that i have bad shyness issues.\\
conclusion: I am extremely self conscious.