No idea if its true or how it works but ive heard that said about string instruments like violin/cello type instruments.
I imagine the theremin sort of requires this in its way as well.
As opposed to something with buttons or physical quanta that predetermine the sound that is possible from engaging them as known without need to finetune or ise ones ear to get it right
All brass require this, as the base pitch is created by the embouchure, and the player centers the pitch this way.
The keys just give them a greater range of pitches as (I believe) an integral of the pitch they’re currently playing.