The problem is that left unchecked, they are going to replace all of the normal games with their tranny shit. And yes, you can say "Well, I just won't play with them, and will play older games," but there's two problems with that kind of thinking. First, "apres nous le deluge" is a shitty fucking personal philosophy to have. When facets of society start to have that kind of school of thought, when they have no care for future generations, then it means you're not going to solve any problems, you're just going to avoid them. This brings me to my second point (although they are bi-directionally related) in that the problem is that if left unchecked, there will be no players to play these older editions in your homebrewed settings. They would be outraged by the fact that you're only including three genders, or that you have monsters that need to be defeated, or that every single person of authority isn't a strong, disabled, trans woman of color. And yes, you can say "hurrr slippery slope," but slippery slope isn't a fallacy and it's already getting pretty bad, so why the hell do you want it to get worse?