It's not the pressure. It's the flame cutting by the high-temperature gases that result from the burning propellant. The reason the 6.5 Creedmoor performs like it does is due to heavy bullets and a lot of slow-burning powder to push them at those velocities and still stay under allowed pressure. Using stainless steel increases the barrel life somewhat, but they still burn the throats out pretty quick compared to other cartridges.
Thanks, but its still not 100% clear to me. You can use many of the same powders to load 308 as the Creedmoor. But I am not discounting your warning about barrel life. I learn something new everyday and thats the way I like it. :)