The cartridge doesn't know the difference. What is different is what happens once the round is fired. As the bullet moves down the barrel, the less that happens to the rifle in the way of disturbing things, the better.
If all that happens is normal barrel vibration (unavoidable), proper bedding likely can counter it. But every thing you hang on the barrel by way of gas cylinders, pistons, and the like will affect the barrel in a different way, making compensation very much more difficult. And then, at some point other parts of the rifle become active moving parts, not just static parts. Pistons move, operating rods start flying, and all while that bullet is still in the barrel. Each movement creates its own vibration and affects, in the final analysis, the position of the barrel when the bullet exits.
All this can be dealt with and controlled, but it requires more analysis, more time, more work to do so than with a simple bolt action. Add in the weight factor, and things get worse. One criteria of the modern military rifle is that it be lighter in weight than the old guns. It is not that today's young soldier is weaker than his father or grandfather, it is that he is expected to carry more weight in other stuff, mainly ammunition.
So military rifles today tend to be light, with light barrels. That means more vibrations, and more work to control them and produce accuracy.
Jim