As a former patent attorney, working in various industries, a good rule of thumb is that only 1 in 3 inventions ever get implemented commercially. Back in the 1990's, in the keyboard field, it was about 1 in 10. The chief problem with keyboard innovations, even ones that are demonstrably more efficient, is that its a little like asking people to reverse driving on the right-hand-side (here in N. America), and go to left-side-of-the-road driving. You have to break a lot of ingrained 'finger memory' -- and, to some extent, be sure that your peers are doing the same.
I think, then, for that reason, such keyboards never amounted, as a whole, to be more than 1-2% of the entire market. Literally, 100 different keyboards (than QWERTTY) are outsold, by a factor of 100X by QWERTY