"Possibility of success" is a sliding scale and I don't think it's about guaranteed wins above all else. It's about not entering into pointless situations. If you've never done it before? Perfectly ok, it can be explained. If you've never done it before and you know nothing about it and aren't appropriately equipped to challenge the content? Also not the end of the world but beyond politely informing the person that they should adjust their gear before attempting the content, maybe even making a few suggestions as to exactly which pieces should be improved and where to get them and then leaving the run, idk what else is really being expected of total strangers here? Deep seated rage? Not likely. The person in question is unprepared, maybe they just didn't know, that's what letting them know politely helps to alleviate, but don't expect to then continue a run after being told in no uncertain terms you just aren't prepared to successfully complete it *while pulling your own weight I guess should be added because it could be that they could carry you*. Why does this have to be emotional "Why can't we just do it anyways?" nonsense. There is no chance of success OR your party members are not willing to carry you, which does not make them elitist assholes btw. That's not enjoyable, it's pointless and tedious.