So you believe nine games of starting experience and playing in 14 has no value over not taking a snap at quarterback in a regular-season game before becoming a starter? Then, yeah, we disagree.
Players have said there is a big difference in the speed of the game going from college to training camp/preseason, and the speed of the game goes up another notch in the regular season. Teams do not game plan you as a QB in the preseason. They use vanilla schemes that don't confuse young QBs like they do in the regular season.
So yeah, I think the starting experience Cousins got gives him an edge, because by the time he became the starter he had had the opportunity to experience what happens in regular-season games and begin to adjust to it.
I agree that quarterbacks need time to develop and groom, and I believe this would be the best course for any of them (not just the late-rounders), but if part of that grooming experience includes getting a few starts or some playing time here and there, then that gives them some experience they can build on when it's time for them to assume the full-time starting role.
Cousins' path to becoming a starter IMO was ideal. Get the young, developing QB experience during the regular season and continue to develop him. Romo's was better than those who just get thrown into the fire, but ultimately after being groomed only in practice and the preseason, he was still thrown into the regular-season fire, while Cousins got to play when little was expected of him because he was the backup.
Again, that's comparable to Dak. Romo was supposed to be the starter in 2016, so Dak having to step in as a fourth-round rookie gave him a chance to experience starting with little expected of him. But like Cousins, the game caught up to him some his second season. I hope having more starting experience than Cousins, though, keeps Dak from experiencing a mediocre third season as well. Hopefully, his stats also will end up being comparable to Romo's numbers in Years 4-6, maybe a year earlier than Cousins was able to do it.