The threat here is to the philosophical conceit that you can trust strangers -- not via a network where people vouch for each other, but just by averaging large numbers of them. Democracy makes good things happen. It's a beautiful idea, the philosophical gem of the last two or three centuries, and it works well in some contexts, and certainly is better than what it replaced... but its success has resulted in overapplication. It certainly can't withstand an army of malicious bots.
I have enjoyed the fact that the absolute political freedom of internet communities has allowed for myriad experiments in government on the sort of timescale that allows for lessons and improvement. The core conceit that people, in large numbers, are basically good and wise was the core philosophy that ruled the internet of ten or twenty or thirty years ago, with its open networks and upvotes. But it seems to me that we have all collectively been coming around to the fact that moderation, and reputation, and credentials, and curation, all have some serious up sides. Tyranny is certainly a problem, but maybe kings and aristocrats aren't all bad.
The bots are really only a threat to communities that haven't figured out yet that there is a balance here, a give and take between the individual and society. That zero contribution should equal zero power, that a high degree of influence ought only be achievable by long and faithful service, that trust is something real people have in each other and that proxies for it can always be gamed, that social status serves a very real and useful function, and that destructive behavior should be met with extreme prejudice... but at the same time, that outsiders can sometimes say very important things.