I've just thought that since the state of the hidden option is kept individually for every comment at the client side (through cookies, I guess?), it could be good enough to also keep track of unwanted sources and set the hidden option automatically for those instead of needing to be done individually for each comment.

Yes, that I'd like. For me only, of course, and their comments only. One can always chose not to read their posts as OP, but can't avoid seeing their comments while enjoying others' discussions. It'd be healthy to simply don't see them, in my opinion.