They can replace who they want in general, but they never cover the thousands of niche and middle sized subs and thats a money issue, they can’t suddenly materialize thousand employees to moderate some subs. And the medium and small subs actually draw most non bot traffic. Also its estimated that reddit massively inflates user numbers, especially on their “default subs”

Current lemmy supporting hundred millions is absolutely utopian, but its in active development, there would be a way, but i would be very surprised when more than 5% of reddit users would suddenly end up here, lemmy needs to grow healthy and not from one day to the next by a Exponent, that’s a fact. But i don’t think it would take years, more users draw more attention, wich leads to more devs helping to improve the quality.

(oh and i kinda don’t care about the “average users” i care about the top 5% of reddit that contribute 50% of the content and 99% of the mod work)