Anyone who tried to type on an alphabetical keyboard knows that it is pretty much impossible to type fast. Each letter needs to be processed by the brain to find out its approximative position, very much like learning on QWERTY or Dvorak. Therefore there is no gain in learning to type using an alphabetical keyboard. It’s more like the opposite: even if you master it, you cannot type on any other keyboard because the vast majority of them have a QWERTY layout.