I consider 6.5 Creedmoor a product of my generation in the sense that it and the trend around it (efficient cartridges with low bc bullets) came about during my lifetime. My lifetime mostly includes (with respect to firearms) Boomers, Gen-X, Millennials, and Gen Alpha (so far). A Boomer introduced the 6.5 CM and Millennials probably bought most of them.
I'm Gen-X, and my rifle is actually a belted Win-Mag from the Lost and Greatest Generations. My dad, who is of the Silent Generation, was alive when the belted Win Mags were introduced, but too young to be part of the cohort of consumers they targeted. He would have been in High School. He did, at that time, use a 270 on the ranch. I acquired my belted Win Mag by random chance. It was developed during the Magnum trend, started by Roy Weatherby, when big overbore cartridges shot lightweight bullets at 3600 fps for laser-like trajectories and the longest MPBR. There were no laser rangefinders. I am not loyal to it. If I get to use it some, I might gain a sentimental attachment to it, but I have none yet.
For my sons, I bought a 6.5 Grendel, which preceded the 6.5 CM, although I bought it at a time when both were available. In a practical sense, the Grendel does everything the CM does. I don't argue about elk because none of my family are hunting elk all over the place. Deer and pronghorn cannot tell the difference. Later, I bought a rifle in 6.5 CM for my boys. It's outstanding. I can't ask for anything more. I can take it out and with a cold bore, hit a coke can at a known-distance of 300 yards with one shot. I can dial the scope and hit the dead center of a paper plate at 100, 200, 300 yards with successive shots. With a 200 yard zero, MPBR for deer is just about 300 yards. My son took a buck with it at 200 yards without a laser. For longer shots, the laser and dialing becomes useful. Is it an elk gun? I don't care. Am I loyal to it, or is my son? No. I wouldn't sell it, but my son could someday if he wanted to. Would 270 or 308 do the same things? Or 6.5 Swedish, or 260? Sure. Should we shun 6.5 CM for being hipster? Whatever.
I don't think 6.5 CM is even that much of a craze anymore. Certainly, it was for a while, but now there are all the PRCs, the Westerner, ARC, HAMR, Fury, the Backcountry, Blackout, all the different modern straightwalls, Buckhammer, the Legends, etc. not to mention all the 6mm benchrest stuff, PPC, 6x47 Lapua, BR, GT, Norma, Dasher, BRX, UBL, ARC, 6mm CM. Even if we discount the AR cartridges and the straightwalls, it seems like 6.5 CM is less likely to sell today than the PRCs and several new cartridges are vying against them for market share. There's not much reason to hate a nearly 20 year old cartridge in today's world of johnny-come-latelies.