I don’t think user voting in of itself is a problem. It’s the consequences of large negative voting that causes the real problems. In Reddit, a single unpopular comment on a popular subreddit could send a casual Redditor into negative karma which effectively shadowbans them from Reddit. As a result, you see people deleting their comments to stop the bleeding. Controversial opinions are punished severely.
TOTP 2FA is coming in v0.18