Are you on steam on windows?

Ohhhh. I see. So it can actually be used advantageously. Thanks.

Yeah, I'm curious as to why it's not allowed as well. I mean, no one would even want to do something that crashes the game. So why even bother banning it?

Same. Had it on Xbox, decided to start "playing on PC" with the Windows version since I already owned it, realized that it pretty much had the exact same limitations as the Xbox version because it IS just the Xbox version, bought the steam version, started playing 1.1, happy ever since.

A good rule of thumb is that all valid NMG runs are valid 1.1+ runs. But not all valid 1.1+ runs are valid NMG runs. So running on 1.2, avoiding beppi skip and avoiding Luigi Swaps pretty much keeps it valid for both categories for the most part.