Yeah I do not doubt it - I've seen that happen in every Reddit sub I have ever visited. Quite frankly the problem is a general "information security" one for which there is much theoretical support - e.g. how does a cell avoid manufacturing a virus, how does a body avoid letting its cells grow malignantly, how does an engine avoid letting its parts bash around and destroy itself after one slips loose from its fashionings? Pro-Tip: most often the answer is "it does not", and the system gets destroyed. To counteract such contamination takes EFFORT, which is only possible b/c we do not exist in a closed system and instead have far more energy being thrown at us than we currently use even the tiniest fraction of. Nature has demonstrated SOME solutions for us, but ofc the wider issue remains, and any time the tiniest crack in the armor appear, something will manage to slip in, that is just entropy and there seems no way around THAT (possibly even in theoretical terms, at least within this singular universe; though extremely high efficiency could substantially flatten the curve).

Here on Lemmy several people including me have talked at length off and on over the months about how to make a better discussion forum environment where that does NOT happen. e.g. so many people say that karma should not be used, EVER, in an automated manner but I take a different approach. Certainly there should exists magazines that use that approach - like 4chan - but I for one would like to choose to not visit them:-P. Instead, I want people to talk who are vetted, e.g. someone who is not already known to be an absolute rabid asshole who cannot, WILL NOT hold their tongue, and instead delights in ruthlessly making fun of others, confident in the knowledge that nobody will stop them, and others will even egg them on. e.g. I am in fan of moderation, especially if it could be done in a mostly automated way. Wikipedia does this well imho.

Anyway, my idea would fail miserably in the situations you describe, b/c while wikipedia relied on the idea that people are inherently good actors, on the whole, in a place such as hexbear or lemmygrad, they seem to be... not? Innuendo Studies described that AT LENGTH in a video series Why Are You So Angry, discussing the tactics used by 4chan boards that predate the Alt-Right but where those tactics were later refined to work to even greater affect to involve someone who literally controls nuclear technology and could start WWIII on a whim, short of outright treason to stop it (hey, remember when someone did that at the end of the last presidency, and all the Republicans said "naw, don't worry about it dude, you did the right thing"? good times, good times, when WWIII almost began right then and there...:-P). So, moral of this self-centered portion of the story: I am not so smart. The approach used by wikipedia and the scientific peer-review process, does NOT apply when there are "bad actors", especially bots that can be spun up by the thousands and mimic the actions of humans.

Even so, I still think that there is something to the idea of Trust authentication, that is used to such good effect in so many places. It is vulnerable too, as are all things. And the thing I have to always remind myself: any tool can be used to whatever effect its wielder wants, so "those places" can use that SAME EXACT tactic to make themselves into wretched hives of scum and villiany (to borrow a quote from Star Wars:-D), just as other places want to do the exact opposite. The unfortunate part there is that they refuse to label themselves as such - i.e. they call themselves "leftists", the same way that the GQP (laughably) says that it is "Pro-Life", and the same way that those who showed up at the January 6 riots in the USA White House were "defending" (ahem) the Constitution of the United States of America. Even though all of those do the literal, full, and polar opposite of what they say.

Which, get used to it, is their RIGHT to do so, and is a condition that will remain forever - hence e.g. cancer is going to do its thing, and it takes a doctor to force it to turn around; and rioters are going to do their thing, until police or shopowners or whoever stop them; and so on and so forth for entropy to be overcome by effort. Can you tell how I've given up? Viruses will always do their thing, and I cannot cease the production of all viruses in all cells across the globe, I can only do my little part near me, so that is what I do, and I leave the rest alone.