I know we all love finding out where the best massages joints in the Indian subcontinent are but hear me out.
Sure spammers have to solve captchas until they get a high enough score, but what if they had to solve even more? For example, if your score is between between -1 and -5 you have to solve two to make a submission. If it is between -6 and -10 you have to solve three, and so on. It seems like a good way to keep the mechanical turks busy instead of wasting our time reading about dubious health benefits.
Not in favor: If or when we gain users who get negative scores by sincerely representing opinions that most people hate, such rules would act to censor them similar to voat's CCP restrictions.
Reading the title, my first thought was creating a special sub for spam. Spammers get flagged as such, and then every post they make gets redirected to '/s/spammerpurgatory', which has no subscribers, is not visible on /all/, and gives each post a couple of downvotes automatically. To escape purgatory, spammers would need to comment/interact to argue their case, otherwise they just stay there forever, hopefully wasting their time while assuming we can see their posts made to normal subs.