The yellow paint is only really necessary in the event they aren't given enough a time in the design phase. If everything works correctly, you should be drawn towards the correct way to go by visual cues. Having the yellow paint means it's not necessary to indicate with those visual cues which make for a less planned out environment. It is at best a crutch so that game designers can focus on more important things. It should not be seen as an end to itself.
This breaks down for lots of open-world games, although the linear dungeons can absolutely still be done without the line.
Primordial gods are considered to be a step above the other gods, they just don't care enough to rule. Imagine Zeus the God of Thunder trying to fight the primordial manifestation of movement and change. The gods are rulers of the universe, Primordials are the very foundation of the universe itself and could destroy it with a thought.
Even the Christian God before, he was retconned to be the only one, was only given such a high respect because he brought order to a small dot of Chaos and formed the earth. It's like taking a fort in a war while being completely surrounded for miles and considering it "defeating the enemy."