Why do game devs do them??
Who the fuck enjoy them???
Either make a main quest or side quest that takes place in that place or fuck off

Why fill your entire map with ? so your players have to go to each location to solve 20 puzzles, kill 10 bandits, find 5 treasure chests, etc.

And they even make sure all that shit is in your face at all times, it's not optional content if every time you open the map all of it is filled with shit.