My complaints from my time in had to do with clapped out rifles and magazines that should have been repaired or replaced.
This. Directives, orders, budgets, policies, logistics... whatever it is that force unit armorers to be stingy are probably 60% of the "problem" with the AR pattern rifles. 35% of the problem is training, and/or rear echelon troops that don't really understand
any mechanical device can fail, and don't maintain it like their lives depended on it.
Complaints of ME sand/dust that gets everywhere, I take with a huge grain of salt. IMO, most of that is like police chiefs in the news for shooting their own ass, and it being blamed on the holster, or "I was cleaning the gun".
The remaining 5% that legitimately is wrong with the AR inherent to it's design, and isn't support, training, or employment problems (Like my example of giving more A4's and 70gr ammo to infantry working in open spaces), you're arguably just trading it for a different 5% with any other rifle out there, or even more.
Bullpups? You get wall hugging and cornering problems in MOUT, and mag changes are slower.
AK-based? Heavier, arguably less inherent accuracy with a long stroke piston even when it's made to 1st world standards. Maybe giving up slide-in magwell for slower rock-in operation.
SCAR or some other polymer uber-gun? Actually heavier than a DI AR. And well, the HK G36 is not all it was cracked up to be after all, heat and melting issues turned out to be a problem in extended firefights.
Round and round we go.
I've heard similar complaints.
1. Those guys didn't autopsy, and sometimes didn't even go look at, the bodies. They are guessing at what happened internally.
And
2. I've been on a lot of military ranges. A badly placed shot with a .50 will go through as well. A lot of these soldiers are missing, or hitting on vital parts.
And this.
Misses counted as failures. It's easy to forget you won't get a true immediately lethal shot/stop unless you hit that roughly bowling pin sized area of the critical brainpan and thoracic cavity and/or upper spine. Movement, gear and loose clothing on the enemy will all trick the brain to think "I KNOW I hit him!" etc.
Probably where a lot of the Korean war doubts about .30 carbine came from. Something with .357 Mag energy at 100 yards is nothing to sneeze at... IF it hits the vital area. It's really easy to get grazing shots on skinny PLA troops in heavy winter clothing.