Even in the custom keyboard community the vast, vast majority don't require relearning typing. Whether it's 60%, 75%, split, ortholinear, typing is still basically the same.
Ortholinear definitely takes a non-trivial amount of practice that a lot of people aren't willing to do. So do layers.
The overwhelming majority of people I have talked to aren't interested in using a non-standard keyboard design, even if they are interested in the ergonomic benefits.
There are definitely a lot of us who want more esoteric designs, but we are a relative minority.
