Been exactly this way in most of the world for decades. The idea that flying a Cessna round the bush is the only way to prepare people to be Airline pilots is anachronistic baloney.
Not saying experience GA guys don't make good airline pilots, as do experienced service pilots.
But taking someone from scratch and specifically educating and training them for the job they will actually be doing also produces a capable pilot- as the thousands of examples in Europe show.
More than one way to skin a cat and just because "we didn't do it that when I was a lad" doesn't make it less effective.