Everyone here does realize we have seen a 3d open world ish fnaf game that turned out very well and has had a amazing fan reception?(although technically not by scott)
Joy of creation. Yes, theirs a few levels where you dont move around but the majority you do walk around to stop the animatronics.
Its a amazing example of a fnaf game where you can actually walk around. If sb followed that example it would be golden. (although I guess you could argue joy of creation isn't completely open world. But still theirs plenty of fnaf fan games that are open world and levels better then sb.)