Doesn't change the fact it's true. Let's not dwell on that here though.
Honestly the simplest solution is to just integrate some generalized anti-carry/anti-leech mechanic where the entire duty is considered a fail if either:
a) A player is "KO" longer than 60 seconds/fails to revive within 60 seconds of a revive cast.
b) A player is "auto-following" or standing still without being in combat stance once another party member is in combat stance. If a (trash) fight ends without the player doing anything, then they become subject to auto-kick.
c) A player (specifically in 24-player content and frontline content) that "camps" in the zone-in/spawn location without moving after the first player KO's.
This would create an "auto-kick/auto-fail" without penalty prompt. For PotD/HoH, it would eject the player and not replace them.
If a player is "carried" it would not count as a clear.
Because you make PotD/HoH 33% harder without a 4th player. Unlike most 4-player content where you can usually sideline one player and it just takes longer, if you sideline someone in PotD/HoH, and the other three players KO, the dungeon is effectively a fail, and you have to go back to floor 20 or 50. One bad player can put you back 50 floors for PotD.
There are two specific playstyles for PotD/HoH, one is "kill everything, get all the chests" and the other is "kill things till the portal opens and then make a beeline to the portal, killing things that engage the party as they go. What is being complained about here is the player who goes to the portal, without even fighting anything, which I've seen happen when the exit portal is within two rooms of the entrance. Sometimes entire parties make a beeline to the exit portal once it's unlocked, and that's usually when someone accidentally trips the spawn trap.
It's not reasonable to ask parties to "not open chests" when they aren't at 99/99, they will because they're not at 99/99. If that triggers a trap, then you're just going to have to deal with it. If you don't want PUG's doing this, form a static.