There is so much more that goes into accuracy than twist rate and barrel thickness.
Accuracy is the measurement of how close to the target something is, which is different than precision. Precision is how repeatable a given measurement or observation is. Something can be accurate without being precise and vise versa.
I'd like to see somebody provide the manufacturer's acceptable tolerances on chamber size, bolt face size/design, headspace... the list goes on. If it can be shown that the tolerances of one manufacturer or action design is looser than the other or whatever, I might buy into something, but for now, all I see is a bunch of LazyBoy Commandos telling me that the Mini-14 is an inaccurate gun. Provide me with some evidence as to why the AR-15 is better or worse than the Mini-14 design and I will probably take your side.
Maybe it's the alcohol talking at this hour, but unless you can put down sub MOA groups with your AR and factory ammo, I don't care if you say it's accurate or not. You are the limit, not the gun. Note: I use AR's for the measurement of accuracy, not the Mini-14 because I know more about them an their usual performance standards.
Science, people. Science. Don't be afraid to think for yourself.