The problem isn't having comments on your blog, it's having locally scoped identities to comment on your blog. It essentially removes all cost for "destructive" participation, whether it be spam, harassment or other trolling.
This is solved either by moving commenting entirely off-site to a larger network, or by using identities from a larger scope.
This is solved either by moving commenting entirely off-site to a larger network, or by using identities from a larger scope.