Niche subreddits are usually good, unfortunately when a subreddit becomes famous lots of people start posting without learning the etiquette.

Moderating a big subreddit is not easy, you can go from having several chains of comments removed (eg. r/science) to getting flooded with bots (eg. reddit.com).

Reddit is becoming more and more dead as time progresses, I'd say its high-mark was the mid 2010s, until 2017-2018 or so.

Of course that its actual traffic might still increase for some time, but it has lost the (counter-)cultural ascendency that it used to have. That's what you get for hiring a former Atlantic Council member as your "policy director".

Reddit is more like HM than a social network.

No, it doesn't. On est bien avancés là hein ?