there should also be email verification and non-breakable captcha (like
https://www.keycaptcha.com/ - friendly for humans, deadly for bots). this would increase time for creating an account for sockpuppet masters. most of them will be gone. the whole altcoin section is going nowhere without things like that.
email verification makes it more difficult for people to operate anon. The ability to be anon is very highly valued. A more difficult captcha is going to be more difficult for legit users.
If your altcoin has actual potential/value then over the long term people will see that and will ignore the trolls.