If you have good neck tension when seating the bullets, I don't see how a crimp will improve things. But since the Nosler folks have no idea if a person will notice or not notice something like that, they probably hedge their bets by telling folks to crimp so a bullet can't get pushed deeper into the case under recoil and chambering, which would increase pressures.
You could experiment. Load without a crimp. Fill your magazine, then fire all the rounds except the last one and measure it again. Is it any shorter than when you started? Then you should probably crimp as the bashing back and forth in the magazine is pushing the bullet further into the case. If it remains the exact same length after all the rounds above it are fired, then you are probably safe to skip the crimping process.
I do believe rifle ammo going through a semi-auto should be crimped, but that isn't applicable in this instance since you are using a bolt gun.
And - I guess I feel compelled to say it - revolver rounds need a nice, deep, roll crimp. If a bullet creeps forward, the gun quits working pretty quickly and that's never good.
