Nothing wrong with the 6.5-06, 6.5 Sweed, .260 Rem. or any other of many cartridges. The Creedmoor legitimized the 6.5 in this country. The Sweed is difficult to get brass for and is a handloading proposition. The 6.5-06 is a handloading proposition. The .260 is like so many other Remington adventures it was a stepchild. It is also largely a handloading proposition. The Creedmoor is supported by good factory ammo from the start. It was originally offered in a fast twist to stabilize heavier bullets.
Perhaps it's greatest contribution to the shooting public is a splendid topic of largely useless debate on the merits of just about every other cartridge ever conceived.