Admins are too busy to ban spammers all the time. So allow regular users to silence those spammers.
At the moment you need 10 CCP to make link submissions, but they can still post comments with links to their spam site. So prevent users with negative CCP from posting comments that have any links in them (or alternatively, don't make their links clickable).
Or to prevent spammers from making new spam account for every comment. Set the same 10 CCP limit for posting comments with links.
Let us take this spammer as an example https://voat.co/user/hddizifullizle/comments has been doing nothing else but posting spam links in the comments. Has been downvoted to hell and most likely reported several times. But he can still keep doing it without any problems.