They are already arriving to some degree.
The difference being is that Lemmy and other similar services have zero controls or ability to handle bots or bop traffic if those bots were bots from 2014.
Not bots from today.
It's a bit of a problem and honestly with increasing bot traffic across the internet and fedaverse being extremely vulnerable to it It's absolutely bat shit insane, but I don't see any other option than somehow having some form of human verification.
It's a problem