I think we can all agree that it's not normal that everyone risks stumbling upon porn or guro when going to a comment section.
So here's a simple idea to make it a bigger pain the ass for the spammers: New accounts may not embed images in comments until they have posted a few comments and some time has passed. If they try to, they will be prompted with a simple popup message: "You must post more comments to gain the ability to embed images".
I don't see spammers actually using brain power to post normal comments. And if they try spamming gibberish in obscure articles, it would be obvious to spot and curb them before harm is done, assuming moderators can see a list of all recent comments on the site (please tell me they at least have that since there's no report button).