A social network needs enough users to actually function. In the early days, Lemmy/kbin/associates were too quiet to be appealing, so there was a constant push to bring in new users. As this is a Reddit clone social network, inevitably that means hoping that Reddit users will come across.

I would argue that Lemmy et al is already at a high enough number of active users that there's a basic critical mass; that there's enough activity here such that a new user would find plenty to keep them engaged. It could certainly stand to be much bigger still, but the pressure to grow is much less intense.