It's a marginal benefit, but it's still a benefit.
The more significant factor than "qwerty vs colemak" is that the thumbs aren't able to achieve much with the hands rested on home row. They can hit spacebar; and to be useful for anything else, the hands have to move.
Whereas, with keyboards like the Moonlander, the thumbs can reach 2-3 keys each.
Albeit, regarding vim's 'hjkl', vim makes it very easy to quickly move around a single line, so h/l shouldn't be very common. For rapid vertical movement, 'easy motion'-style stuff is neat.
I just don't see it being that beneficial. Is like thinking you could be a better pianist if only the keyboard was arranged in a different way. Almost certainly true at a very technical level. Hard to think that is the actual limiting factor for most people, though. Even on the piano, I found that I am better with certain fingers than others, but that it just doesn't make too much sense to worry about that at the beginning.
I think that's much nicer than having to move the hand or stretch with the pinky in order to hit backspace.
Whereas with the standard keyboard layout, you can't keep your hands rested on home row & reach those keys.
Maybe "whether it's worth having such a keyboard" is down to personal preference or whatever, sure.
The nice thing, though, is most of the other key choices are mnemonic. "C" for change, etc. Such that you really can keep moving fairly well by sticking with the conversation you are having with VIM.