It's not about adapting to change. It's just as valid to tell a kid they can't use "good" and "bad" in whatever they're writing or discussing. The adaptation is understanding that those slang words essentially amount to the same things because that's how kid's slang works. You're not conveying any rich meaning by repeating sigma over and over for whatever you think is good and mid for bad.
On that list the only complex idea is mewing, but the fact that it's complex means the kids who didn't understand its complexity have stripped it out. That's because it's not, in of itself, an actual slang term.
You're mixing up kids slang with code switching. I don't find them to be equivalent at all. That's the greater point I was making. We use the word slang pretty broadly, but in kids it's quite shallow. They rely heavily on context because they don't really have the vocabulary to do otherwise.