I think people come at the caliber question from many perspectives, and those nuances can definitely show one caliber is better than another.

I think comparing 6.5 Grendell to any assault rifle cartridge is a farce. Grendell was made to be a long-ish range cartridge in an AR-15 sized platform. It is impractical as an asslt. rifle cartridge with it's shoulder position and angle. It's really a specialty match/target round. 6.8 would be a better comparison.

I'd say the biggest misconception about the Blackout is it's dual role. Many believe it was designed from the onset as a suppressed cartridge.

The Blackout sprung from the 300/221 and other wildcat versions of the original round, the 300 Whisper. The Whisper was always meant to be a dual-use cartridge. Suppressed with subsonics for sure, but also a 7.92x33mm Kurz clone for the AR, so troops could use it as a true "assault rifle." It was only meant to be combat cartridge to 300-400 yards, and less when suppressed, perhaps 75-100 yards.

As firearms/ballistics enthusiasts, we get caught up in BCs, trajectory, effective range, velocity and energy, and other minutiae. We often forget the intent. Blackout was never meant to be a hunting cartridge, but it works, within it's limitations... It is a superior cartridge to the 7.62x39 M43, because it has 90% of the performance with 70% of the recoil, which means follow-up (or full-auto) shots are more controlled. (Ever shot an AK on full-auto?) When it comes to 5.56, I think the only advantage Blackout has is suppressability, but the 5.56 definitely wins at distance usefulness.