I’ll take a slightly more reasonable approach to this whole argument, as there is no point arguing the merits of either caliber, as they’re both worthy in sensible, real world applications.
My whole reasoning behind Grendel, and as an early adopter of the Grendel and owner of multiple other 6.5 platforms, is about managing what have been limited resources in the supply chain. I consolidated my rifles, bullet and brass inventory to address only 6.5 and .224 calibers.
If I shot a multiple of 6mm platforms, ie. 6GT, 6CM, 6 Dasher, etc or others, I’d likely pick a 6ARC for an AR15 build. However, I went Grendel long before the emergence of all the other 6mm choices and haven’t looked back for a minute. Grendels I’ve built handle everything I want out of them for my applications, and if not, 6.5x47 or CM are at the ready.
For me, it’s been about careful and selective resource management. Pick your dog, but little reason to fight about it.