The problem is that as the good content becomes harder to find, the people who actually create that good content are less and less motivated to contribute. Thus you end up in a death spiral of memes and circlejerky injokes.

Worse, a lot of the expertise is fake. Like, in the two games I'm playing right now I'm finding that the communities on Reddit that serve them end up being wrong more often than right.

Finally, as the community overgrows its mechanics, visibility becomes ever more reliant on timing. Thus, you can say something insightful and relevant and be ignored while a not-great pun shoots to the top because more people saw it. Also, more people are under 15 and have no real appreciation for, you know, knowledge especially when it has to compete with fart jokes.

And then you recognize that any time you say something useful about anything and it actually does get noticed, some bot is going to cross-post it to where trolls eagerly await the opportunity to make you regret contributing at all.

It's been years since I've felt motivated to contribute to any subreddit ostensibly about any of my professional expertise. It's basically an excuse for a twelve-year-old kid to insult you and force you to explain standard terms while everyone calls you mean for using words they don't know.