What were the main attributes that led to varying states of whelmed?
One reason I love text discourse is that it gives me time to thoughtfully respond. My wife is super witty and can be instantly funny and social when she wants. It takes me more time to match that sociable wit.
My hunch is that wit-rate would be a contributing whelm factor.
Some of them were far more manic in the flesh. Email and Usenet hid aspects of what we'd now call spectrum behaviour or ADHD. That was the over whelm.
Otherwise, I'd say it was that people can be less rounded and interesting than you like in an amicable and two way relationship. It's easy to mistake a dialogue to specific intent online for some kind of connection when it really isn't. If they have 50,000 followers (hate that word) and you mistake being 50,001 for some stronger binding, prepare to be disappointed.
I will say that I've also experienced really good, relatable responsive engagement with my heroes and heroines, it's not uniform. It helps if you can meet them in a room of common purpose, not one solely designed for them to showcase in. Then, they're just ordinary people like you, mostly. If you're careful.
Wit: I have "esprit d'escalier" and so only think of the Bon mot on the way out the door.