Many years ago airlines such as British Airways did a similar thing. Take a bunch of people with little or no flying experience and take them through all the qualifications before eventually letting them loose in the right hand seat of anything from the HS748 to a 747.
When these people hit the seat they had very few hours compared the ex-military guys. People didn't complain then. In fact, If I remember correctly, getting a cadetship as it was known as a well regarded path into BA.
so what is so different?
BA (and many others) in Europe are doing it now, let alone many years ago. It tends to lead to the right seat of an A320 now. It works very well.