I have to admit I am not a fan of the double down in high school cheer.
My opinion (and I graciously admit it is opinion only) is that they were not be doing taught/performed correctly. They had also become the "end all, be all" skill for dismounts. So, despite the fact that a high percentage of the kids performing them had no business doing so, almost everyone was doing them, janky or not. There were also a significant number of concussions occurring to athletes in various stunt positions from double downs gone wrong.
When double downs came out, it forced coaches to be more creative utilizing other, legal skills to dismount stunts. I think it completely changed routines for the better. I would much rather see them stay out, and these creative skills stay more prevalent.
again, that's just an opinion.