It’s mentioned in this really good Verge article about SEO. I don’t think it’s a good sign for Reddit to just allow such blatant spam and makes me think how much subtler spam is out there too.
I’ve personally noticed more a few times in old threads you’ll find a comment made months later that’s recommending a product.
Will it? At least instances can defederate, although as we’re seeing, unless instances are very small, admins are proving reluctant to use the nuclear option.
I have hope that as Lemmy matures, admin tools will get better and more granular - like options to defederate communities and not whole instances.
Reddit has no motivation to improve in this area, and they won’t, until it’s too late.