The would just create a brigading problem.
Political subs could encourage their members to join lists of hundreds of subreddits and all vote for picked candidates. Coordination could happen on some other site as well.
It could be limited to active high karma participants of the community, however anyone can game that with GPT powered bots.
Another possibility is to have yearly oustings instead of voting mods in.
At 90% disapproval mods get kicked out. This along with brigading detection should cover damage by bad actors for the most part.
To prevent the use of bot farms (or people farms) to stockpile votes, maybe we could look to the field of sybil resistance and digital IDs?
Stack Overflow has been holding moderator elections for a while. How do they do it?
It's a subreddit, not presidential nomination.
That's the point of my comment, really: this isn't just some site on the internet anymore.