I don't get why people have to do it in DF parties?

People asked for PF, they got it.. And now they won't use it?
Chances are that with a PF group, you can cap much faster than doing a roulette followed by repeated Brayflox HM runs, including the waiting for a full party. Especially if you go for the traditional BLM+BRD or BLM+BLM dps set ups.

Just stop being a dick to people you don't know, just because you'll probably never see them again.