It takes forever to farm a decent hephasto and lots of people bind Lester the tormentor or dudes from Uber runs. But having to find a decent demon every time you start a game would not be fun whatsoever. And warlocks are squishy as hell without a decent demon. Its a bad idea. Period.
Then again, i feel like i dont want to pvp because i dont want to lose my fana cursed heph, maybe if it doesnt matter now itll be good to just bind a new demon each game rando