Besides the old style Piano keyboard, and the Pashkuli keyboard there are hundreds of different ways to convert finger position to pitch: Bandoneon and similar knob keyboards, flute, sax, oboe, guitar (multiple common tunings - drop-D, etc) violin, ... And this only is the European influenced bunch...
There very obviously is no "cure"
Only the Theremin is straight
-Michael (Sorry I could not resist, even if you should not answer to a post that claims something is "flawed", while this obviously just is the personal impression of the author, and hence proves him a troll.)