Look, Dreamcast, I know that whether it's rifles, obsolete gaming platforms, or operating systems you like to try to play the rebel who's going against the grain of traditional wisdom. I get that. You're probably also a fan of Betamax VCRs. But in your attempt to be the outsider with a new point of view, perhaps you ought to put some thought into why many people believe as they do.
However, in reading your posts it seems clear to me that most of your sessions with AR15s don't rise much above weekend trips plinking at the local range, and I simply do not see any evidence that you have enough direct experience with running rifles to be able to offer up an informed opinion.
Nor can I offer up an informed opinion on the use of AR15s by the military, or in places like Iraq. However, we've got a number of people on the forum who've done so and have not reported the problems you claim.
Furthermore, speaking within the confines of my own experiences, I've been volunteering as an assistant match director for a local monthly tactical rifle match for over two years now. Additionally, I was a participant in said match under the previous match director, a man who'd forgotten more about rifle craft than any ten members on this forum will ever know.
He shot an AR10. His wife runs an AR15. Nearly every competitor at this match runs AR15s, including myself. I have two AR15s that I've run multiple thousands of rounds through, often times going hundreds or even a thousand or so rounds between cleanings with none of the claimed reliability issues that you continuously harp on in thread after thread after sourceless thread.
The match I volunteer at is held at a range in a high desert climate with fine blowing sand, and some of the matches have included whipping significant amounts of that sand into the air, including the actions of competitors' rifles.
I've run AR15s so dirty you could scoop goop out of the action with your finger, yet the guns still ran. I've had the opportunity to shoot one of Zak Smith's suppressed AR15 rifles. In case you didn't know, suppressors tend to toss a lot of gunk back into the action. Zak's rifle could easily have been placed in the top three dirtiest rifles I've ever seen.
Yet it still ran.
I've run AR15-pattern rifles at national-level 3 Gun matches for going on five years now, and have yet to encounter a malfunction that wasn't related to ammunition. The vast, vast majority (well over 90%) of 3 Gun competitors are running AR-pattern guns with the direct impingement gas system in them. If ARs did not run, these competitors, especially the best ones on the line, would choose another rifle design.
As an example, the wind and blowing sand at this year's Texas Multigun Nationals was easily some of the worst I've ever seen, yet there were not widespread reports from the over four hundred competitors that this sand was causing their guns to fail.
Furthermore, AR-pattern guns are the overwhelming choice of competitors in nearly every sport where the rifles are allowed, including Service Rifle, National Match, ODCMP, 3 Gun, Tactical Rifle, and other sports. AR-pattern guns are overwhelmingly used by law enforcement and military folks, and have passed muster in failure tests that are far more exacting and detailed than any someone like you or me will ever be able to undertake.
If these guns were not adequately reliable, none of the above people would choose them, especially competition shooters, who could opt to run nearly any platform they wish.