I do get why it is there in the first place, but 20minutes is way too long. Games like Fortnite doesn't have any penalty - you can hop in and out any time you want. They have like trillion of players, but here in BGs, sometimes the playing environment isn't healthy.
Sometimes your own group doesn't have a clue, sometimes the other group is pre-formed of DKs and healers. Sometimes people play deathmatch in other games. It's no fun to play there. "Deserting" from that is legit. Why should I waste my time in that?
If I opt to not play the match... then I waste a slot for someone else AND I get inactivity penalty. Sure the game doesn't know how many toxic players is there or if it is toxic at all, but having 20mins is waaay too much for that.