It really depends on what the party wiped on. If it was a common place to wipe, people generally aren't so quick to leave. But if it's on a part where anyone who has cleared it should know the mechanics and could have easily been avoided, that's a pretty clear sign the party isn't going to clear, so that's why they leave. There's a lot of people who were carried through content and never learn the mechanics properly, then they go into Party Finders and screw up the whole thing for everyone.