Ballistics aside - because in terms of ballistics there is nothing new from new cartridges, there is only new from bullets, bullet shape , bullet construction and platform .
Creedmoor is a latter day shooters phenomenon.
A phenomenon is something that takes the world by storm, and is immensely popular.
I say it is a phenomenon because there has been a convergence of industry focus and effort to generate a perfect storm around the cartridge, that no other cartridges in my lifetime has had.
This convergence of effort has produced off-the-shelf rifles that can be mated to a scope, zeroed, and taken to a shooting competition with factory ammo, and score for place. I don't recall any other commercial caliber offering having that to say for itself.
New shooters have found that they can go buy a rifle and scope, buy ammo, and hit steel out past where my eyes can still see.
Consider the platform. A Sabatti tactical in 6mm Creedmoor, from the factory, feels much heavier than my 500 Jeffery which weighs 12 pounds. The barrel is totally free floated. Barrel profile is a straight tube. The rail is integral to the whole assembly. There you have the basis of incredible repeatable accuracy potential.
The factory competition ammo available is as good as any a reloader can produce. Consistent, consistent, consistent. And in the US, the cost of investment in reloading equipment takes really long to recover versus buying factory, so why bother reloading if all you want to do is shoot.
This is the angle that the young shooters, who don't have experience with other calibers, and don't know how to reload, are coming from in the Creedmoor discussions. So when you say that caliber ABC is better than a Creedmoor, these shooters will think you're smoking something unusually strong, because they don't see any of those caliber rifles on the shelf that they can take to a long range match with factory ammo. Like, where's the 10-round mag, dude ? Like, dude, there's wood on this rifle !
Credit must be given where credit is due, and it's all due to the manufacturers that have produced innovation and quality, taking sport shooting capability to levels previously unknown.
The Creedmoor cartridges could not have achieved this surge in popularity and adoption on their sole merit.