It's NOT Ford vs Chevy to someone who understands how they work. That line of reasoning only glosses over what's happening under the hood - or reveals a lack of knowledge about what they do.
How the bolt carrier is moved by the action of gas in a cylinder is less important then the controls. If, as was said, it's the operator, again, I point out that the AK isn't present in the top ranks of 3Gun shooting. The controls are all wrong and impede the shooter.
A car that has to be hand cranked to start isn't going to be as fast off the line when you are lined up across the road from where they are parked. That's called Le Mans start - the drivers spring across the road, crank up and move off.
The AK hand crankers are going to be consistently left behind, and are, which is exactly reason for the results we see in OPEN completion. Shooters aren't stupid, they pick the gun which helps them win, and the AK doesn't. It's slow and cranky.
By the way, did I mention the safety yet? You can't thumb it off with your finger on the trigger very easily. Another fail.
Can the AK be improved? Yes, and they are on the market. Like, left hand charging, and safeties accessible to the thumb of the firing hand, and robust rail bolt covers that don't shift around. All of which come standard on the AR. In point of fact, copied precisely because the AR has proven to be better in the control layout than most combat rifles. So much so most combat rifles currently available copy the control locations.
How about mounting a free float over the barrel?
Or replacing said barrel with something in an alternate caliber? Can't be done without a press and the ability to set headspace while doing it. The AR simply drops into the upper, the barrel nut tightened to hold it and let the gas tube pass. AK = expensive barrel press setup, AR, a vice on your workshop table.
The AK is a primitive copy of the German assault rifle meant for low tech industrial capacity - if you shoot it out, you just get another. The AR was designed from the ground up as a high tech rifle using modern mass production methods and repairable. It's modular reasoning is why we have so many variants - it's certainly done better than HK's attempt at making roller locking a interchangeable standard.
M16's are surfacing in the hands of Vietnamese mountain villagers that were handed out to them in the first missions contacted by Special Forces - still working after 45 years. Pretty rough for the wear, but operating full auto weapons. I haven't seen AKs from that era - it's certainly not impossible. Please link to any as a counterpoint.
And as an aside, no, you DON'T have to clean the tail of the bolt. It contacts nothing and does nothing to change the operation of the weapon. Any more than you have to scrape the carbon off the pistons of your daily driver. If it builds up, it disintegrates and flies out the exhaust ports on the side of the BCG.
Ex. Filthy 14, which was cleaned twice in 60,000 rounds last I checked. No stoppages due to carbon on the tail of the bolt. Just because the armorer doesn't want to do it for clean room inspection standards doesn't mean it's required for you. Weapons cleaning in the military is an item to fill a unused part of a training schedule. It give supervisors a break time to go do paperwork.