It's anti-escapism.
When you play a tabletop game, your own politics don't matter much. You're in a fictitious scenario and can explore a world that isn't yours with someone who is not you. You can be someone you aren't, do things you couldn't, and broaden your world through the power of imagination itself. However, that very aspect of it makes it exceedingly dangerous to authoritarians. You can upset the paradigms. You can see things from an angle you'd never allow yourself to do in the real world. More critically, you can subvert the authorial intent and purpose of the developers through the awesome power of Rule Zero:
If you don't like a rule as the GM, change or don't use it, and as long as the players know you're doing that and why, you're golden.
It's more than the GM's ultimate sanction against munchkins who would break a game system: It's basically the acknowledgement that as the arbiter of the game, the GM has the fiat to supercede the rules (and bear all responsibilities that come with that power). The thing is, that also means the GM is free to reject the entire ideology a work is trying to push, if they so choose, completely subverting the intended message of a work. That's a big problem. If political messaging is so important to a work (and make no mistake: To the shitheads doing this, it is), then they can really never afford to give a reprieve, lest any GM who wants to subvert their intentions. Since they can't flat-out mandate that a GM do exactly as they say, they go directly for lengthy treatises on why you can't and shouldn't do X.
Escapism has to be tilted to push the narrative, or it will be a refuge from the narrative, and the idiots pushing this nonsense can't have that shit.
