Honestly, I think you would see a lot less ragequitting if people who are new to a dungeon would take the two seconds to type "Hi, first time here" instead of saying nothing and then causing a wipe because they don't know the mechanics.

If you're new and say so, I'll be happy to explain bosses to you. If you just stay silent and wipe the entire party, I won't ragequit, but I will be grouchy for the rest of the run and will also be less inclined to help you out. You want courtesy, be courteous to others. You'd be surprised how many people are willing to help out if you just say that you need it.