Simple.
Life is scary.
Talk, chat, pretend is not scary.
I could have joined here and told everyone i was a member of MI 5, or whatever number they are up to, and i was a British intelligence agent in some exotic foreign country and i use a device that shows my IP as in the US so i can hide, and just build myself up as some exciting guy that everybody wants to meet, and set up meetings then cancel because i had to save the queen, then jerk off to the excitement of meeting a couple.
There are entire communities online, SIM cities, where people never leave their basement and live through the characters and life they create online.
Those people would never survive an in person meeting.
Another problem that i see is, i do not see many people in this lifestyle that have any interest in someone who is inexperienced and might hyperventilate on the first meet. This forces the inexperienced to lie and get themselves into something that is moving a lot faster then they can handle.
If i ever got any of you to just meet me, even if i knew nothing was going to happen, just meet, i would expect to hyperventilate and die before we even met. I think there would be a good chance that i woud become physically ill before we met and not be able to meet.
To answer the question, some get off on the chat, some cant function in society and some are inexperienced and scared to death.