Answer: corporations don’t tolerate unexploited value. Online communities are rather good at gathering value, over the years, as their users add knowledge. That makes corporations grow their eyes and say “DAMN! Look at all that value that I gathered! It’s time for me to reap the profits!”.
Reddit’s structure: I think so, too. And, more importantly, it’s something that “the Fediverse forums” (Lemmy and Kbin/Mbin for now; SubLinks and Piefed when they join) should eventually deal with.
Why you left - yeah, the environment doesn’t “feel” cooperative any more. Your example seems to me that the user was disingenuously (or worse, idiotically) disguising a subjective opinion (XYZ is bad) as a question; that’s bread-and-butter in Reddit nowadays, sealioning there is mostly through feigned ignorance.
up/downvote counts - it’s a bit less creepy; they add/subtract a random number to the actual score, mostly to prevent karma farming. Still opaque though, a bad thing in a collaborative environment.
[Not quoting for succinctness]
Answer: corporations don’t tolerate unexploited value. Online communities are rather good at gathering value, over the years, as their users add knowledge. That makes corporations grow their eyes and say “DAMN! Look at all that value that I gathered! It’s time for me to reap the profits!”.