Your rant seems to imply that the parent cartridge of the 6.5 Grendel, the 7.62x39, would also be ineffective. It lacks both velocity and mass, given the Grendel’s notional bullet weight at 123 grains and the Russian round at 124 grains.
Of course, this isn’t true.
This, followed by “I haven’t shot the Grendel,” doesn’t give much weight to your analysis......
I question all these attempts at bigger diameter AR cartridges.
As a pragmatic person, who recognizes the need for speed, and mass, and bullet design in an effective chamberings, they lack two of the three.
