On the flip side, there are some on the shooting forums who seem to think 1 MOA is some kind of almost unrealistic feat. "Show me 10 consecutive 10 shot groups before I'll believe it" or something like that.
Just because the shooter can't shoot MOA, or half MOA, or whatever every single time doesn't mean the rifle can't do it. Some shooters will continue to shoot when the wind kicks up or shoot ammo that isn't capable of high levels of accuracy. Some shooters don't understand parallax. Some shooters don't understand how a barrel walks as it heats up due to rapid firing. Some shooters don't understand how chamber temp can effect rounds allowed to heat in a hot chamber. Some shooters don't understand the difference good glass of adequate magnification makes... or the human factor behind the adage "Aim small to shoot small".
The point is there are optic, ammo, human, environmental, and procedural factors that if addressed, make higher levels of accuracy achievable.
Personally, most of the time, when someone claims they have a sub MOA gun or whatever, I just assume they understand these factors, have reasonable skill, and do their "record" shooting accordingly.
I understand what you are saying about the absurd claims. However at the same time, I do tend to question the shooting abilities of the few who offhandedly question every claim to what seems to me to be realistically achievable results.