While the other replies are not incorrect, what they describe is users on Reddit posting on different subreddits.

What I am talking about are lots of niche subreddits (many even about the same topic!) thus that out of the few people that are here, there is simply no content, let alone discussions of the present content.

Ooof… That is terrible. Only decline. I expected it to grow at least slowly, but this is just sad. And makes the dozen (niche even) duplicate sublemmies even worse. One sublemmy for every person to take to themselves.

This is one of the things where GPT really helps a lot.