This!, its amazing how some people want to drag you into their world and have a huge discussion when all you want to do is point out some part of their idea your dont like.
Yep It's some kind of logical fallacy where they try to discredit what you're saying by asserting that you must have some kind of solution in order to justify identifying a problem. It feels as if they try to 'prove' that they are smarter than you are, because you clearly don't have solutions where they clearly do.
It's a weak form of deflection.