Thank you for your response and sorry, "always" was hyperbolic, but it's a genre I remember from at least the early 00's and back then it already seemed to be a very common thing. So it's been around for a few decades at least, and thru those decades what has been included in the genre has slowly expanded.
If we agree that more or less for as long as the genre has been around, there has been a tendency to include more and more bands based on the criteria of age, I guess wether or not one thinks it has utility essentially boils down to how we view language or something. I'm not really big into philosophy, but I think there's a bunch of those guys talking about that kinda stuff