The skills you use and develop to make music are entirely dependent on the repertoire you play.
Why do we learn how to play fast? It’s because we’re preparing for repertoire that requires fast playing.
What if we can’t play fast, and never will play fast? Then we re-think the repertoire. Develop the skills to learn, play and compose slower music.
Kudos to the artist who passively and actively creates new music intelligibly crafted out of a need to battle technical and physical limitations. They are using their skills most efficiently and effectively. They are also freeing themselves from expectations that they must play and sound a certain way.