One of the oldest and stupidest myths about TTRPGs is that the GM isn't a player (albeit one with an asymmetric experience). I don't feel a need to justify this opinion, it's just obviously the case that the GM is a player when you think about it for even 5 seconds.
From a design perspective, probably the worst knock-on effect of this myth is that most games basically treat the GM as "beyond the rules", and a lot of GMs balk at the idea that they should be bound to them. We don't treat asymmetric play this way in any other tabletop gaming situation. It's what leads to dice-fudging, GMPCs, and most forms of railroading.
Of course, you do have your Apocalpse Worlds out there. There are plenty of games that do give rules to the GM. But I have yet to see a game that goes whole hog on the idea that the GM is a player and fully treats them like one in the rules by enumerating the reasonably complete list of ways they can interact with the game at any given time. I've especially never seen a "crunchy" game make any attempt to do this.
Which is a shame! And one that I hope to correct. I don't really have fully-baked ideas to show off, so no details yet.
But I do think that from a GMing perspective, the following rule holds:
A bad GM can make any game bad. A good GM can make (almost) any game good, or at least enjoyable. A game's GMing should be judged by how well it does at augmenting the GM's talents; how well new or mid-skill GMs are able to run it.
