I think throwaway accounts should be banned, or at the very least, there should be a waiting period before you can comment. If you participate with thoughtful comments, you’ll reach 500 within a month. What bothers me is people creating these accounts on a whim just a throw out some garbage, or maybe a valid opinion, and then disappear in the night. If you had to wait a week to post it might lead to massive duplicate account creation, but I think it’s worth considering.

> or at the very least, there should be a waiting period before you can comment.

That wouldn't work that well for sites like this one where reading doesn't require an account. The moment one wants to create an account will most probably be the moment one wants to reply to a post or comment with a salient point; making it impossible to reply unless the account was created with forethought would just lead to the account never being created in the first place ("I would create an account to reply to this, but even if I create an account I cannot reply, so why bother?").

I believe Hell has nine levels; HN downvoteland has only 4.