I am saying this to be a little snooty. Your take is very dismissive to a large group of people whose experiences you don't know. I agree that split/custom keyboards and vim are awesome; I have used them for 25 years. But the idea that you can reduce RSI treatment and everyone's situation to something so simple just isn't true. It is fine to recommend solutions to people who are suffering, but to dismiss their problems as being "solved" comes across as basically calling them stupid for not helping themselves.
I know you didn't say that, and you softened your language, but many people with disabilities or chronic conditions have to deal with everyone they share their problems with telling them their "cure". Its exhausting.
[delayed]
Thanks for saying this. I already use Vim (in my browser too). I've used it on and off in an editor as well. I've tried reading books (like I mentioned in the post) which is something you only do when you're truly desperate. For some of us, our body will only allow so much.
I am sure the OP was just trying to help. I, too, when I started having such problems chalked it up to "surely some adjustments will help". And they did! But it never quite ceased.