Fkusumot, volume of inputs is not representative of actual progression. Controller progression is all about user input.
Consider this, if were playing a FPS on your computer, could you use the mouse to point and shoot faster than using the keyboard arrow keys to move the gun and shoot?
The keyboard has far more physical inputs than the mouse yet the mouse offers a far superior user input given the situation noted above.
Now for a while in the beginning, more buttons were considered progression simply because buttons were the main means of user input. Once you achieve a certain number, the law of diminishing returns kicks in and progression ceased to be made just by simply adding more buttons and eventually digression is attained as user input becomes clumsy and complicated.