A-man, a few years ago, I was thinking of getting into some long range benchrest shooting, 600 yards, maybe 1000. Didn't do it, but I was looking into it, and 6.5 Creedmoor was on of the calibers I was looking at. It's been around since 2007. I did a lot of reading about it. And there was a lot of hate for it 2012(-ish?) when i was looking into it.
The hate back then seemed not to be that it was a bad cartridge, but that it was a marketing gimmick by Hornady. Ballistics are near identical to .260 Remington, and very similar, though a bit faster than 6.5x47mm Lapua, with both of those cartridges already being well-respected for certain benchrest disciplines. So the view was that Hornady had simply created a new cartridge to compete with those other two, but one that offered no performance advantages over those other two in whatever practical use or competitive discipline it would be used in, and then marketed the heck out of it like it was the end-all be-all.
So it wasn't that the cartridge was bad, it was that the cartridge was an over-hyped copycat of two existing cartridges.
By all accounts, the cartridge is fantastic and inherently accurate, EXACTLY like the .260 Remington and 6.5x47 Lapua.