I’m taking about volume of users in the aggregate based on that chart. Not any individual’s curated feed.

Yes, but charts like this are proof of how misleading data can be. While the volume of users interested in gaming is large, the vast selection of different subreddits in every possible topic is what makes Reddit special.

But the fact that a big chunk of the user base is there for particular kinds of content inevitably colors all the other communities. This is why the best parts of Reddit are the parts that either restrict themselves from /r/all (or moderate so aggressively that people who show up from /r/all functionally don't post), or are too small/niche to ever show up on it.

They can actually foster an internal community without getting Eternal Septembered once they break a certain size.