On Reddit specifically, these mods of large subreddits, for example Gallowboob, are appointed by Reddit staff. These appointed mods run hundreds of large subreddits per account and Reddit has quietly banned community moderators who opposed the appointed mods. So it's not like a bad admin of a Lemmy instance as a bad Lemmy admin is simply a random person who decided to run a website. The power-tripping mods on Reddit are a deliberate decision by Reddit.