They also arbitrarily don’t allow you to reply to lots which is annoying. I often have follow-up questions (legit ones, not comebacks or other crap) that I can’t do anything about :(
But I agree, its generally terrible etiquette to downvote something someone has contributed to you if its goodfaith and also, assuming your thing is visible people are gonna see it and your interests are linked so its just silly, bottom-line