Maybe make only people logged into their google accounts be able to vote? Surely that should stop most bots

An anonymous, decentralized reputation system which any service could hook into.

Days later, the HN post "a virus ruined my virtual reputation and I'm now banned from the internet".

That's the secret sauce behind decentralization. Damage from any one actor, including yourself, is limited both temporally and in scope. Each service would get a unique hash relevant only to them and giving them access to only their scope, and you would keep your private keys safe just like you would SSH keys, crypto wallet keys, or any other sensitive data. If you can't be bothered to do that, then a minor hit to your reputation is deserved from a philosophical standpoint, even if we work to make the system robust and resilient.

The idea is that it would take a long time and lots of effort to build a credible reputation.

Someone just beginning to use the internet would either need to slowly build reputation in the most open spaces, or get one or more people to vouch for them through an API.

I want to make it fiscally infeasible to run a mass persona farm.