You're confusing two claims. Lack of proof that emacs default are RSI-inducing doesn't mean that % of RSI-harmed users is not an objective measure of ergonomics.
> Of course, the real questions are "why?"
Are you having trouble answering such a simple question to feel the need to ask it?
But this is again missing the point, which was that there was no "reinvention incorporating the best ideas" because many surface-level good ideas aren't incorporated (same thing with the brighter future bit rotting plans...)