Can't leave boss room after killing boss and completing map. Why?

Where's the logic in preventing us from leaving the boss room after killing a boss on some maps? Just because I killed the boss doesn't mean I don't want to go finish killing the rares in the rest of the map. This makes no sense to me.

This just wasted a high % experience gain map for me, because I didn't know I was going to be locked in the room after killing the boss. Wasted most of the map and the experience modifiers. Very annoying.

People were reporting this 9 months ago, by the way. That is a VERY long time for something this annoying to go unaddressed.

https://www.reddit.com/r/PathOfExile2/comments/1hchlr3/defeated_map_boss_but_cant_leave_arena/