The magazine length dictates seating depth, unless you want to shoot the rifles as a single shot rifle.
I have two sporter rifles that I do shoot single shot, but that's my choice.
I get very good accuracy from my other rifles where I don't worry about getting bullets up close to the lands.
But, your point is well made. Why do rifle manufacturers cut chambers such that the leade is so long that you can't get close to the lands and have the loaded cartridges feed through the magazine? Even with long bullets, you have to seat them deep in the case to fit the magazine. So, the long bullet answer doesn't pass the sanity test.
Martyn