> 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?").
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?").