Even if I can accurately estimate the # of replies I can expect, still the question could be asked - why comment?

But like you said, someone sometimes replies and you get pulled into threads like this - which is somehow way too much fun lol - so agree about commenting to start/participate in such convos.

Personally, more often than commenting, I forward the articles I know will be interesting to people in different group chats. And there is a lot more back-and-forth there.