I think it’s a joke about dead internet theory, rather than userbase size

https://en.m.wikipedia.org/wiki/Dead_Internet_theory

The joke comes from an increase in bot use on Reddit, and the subsequent false positive / false negatives in trying to figure out which ones are bots

Lemmy has that problem too, but it’s much smaller in scope. Mostly because there’s less of a reason to try and control the narrative on this smaller platform, but also because the goals are different. Lemmy instances get no benefit from a bunch of fake engagement, and public upvotes makes it easier to catch manipulation