And therein lies the problem. These people had essentially zero experience using their weapons in the field. The article basically says that every weapon system they had "failed". It sounds a hell of a lot like operator failure to me.
Incidentally, I've used M16s for weeks at a time in all sorts of filthy nasty conditions and never had a problem, even with very minimal maintenance. But then, I was infantry and I knew my weapon backward and forward.
So was I.
I tell ya a little anecdote. In Bosnia, my platoon was practically bored to death. Sitting in a tent on top of a hill for months. Knee deep snow. No reason to go outside. Nothing to do but sit around and look at each other.
Anyway. We had a ADA Humvee attached to us on this hill. Just two guys- an E5 and one enlisted. They rotated down to their main unit about once every two weeks so we got someone new to look at every so often. One of these new ADA enlisted was fascinated that all of us infantry types would clean our weapons regularly "even though nobody told you to". We were like- "well yeah, you gotta take care of your weapon the way you would take care of your c--k, your life might depend on it.".
The guy (I think he was a PFC) decided he would spend a little time cleaning his weapon as well. He could not charge his weapon! The bolt was rusted shut! We had to take a hammer and work it loose. He had been running around with this weapon like that for weeks and weeks. He never knew his weapon wouldn't fire and it had never crossed his mind (or his leaders') to inspect it periodically. His weapon- wasn't!
It's a whole different world in the different parts of the Army.
In the USMC, it doesn't matter. God have mercy on your soul if the Sergeant Major of an Air Wing or Force Service Support Group unit catches you with a dirty weapon, because the Sergeant Major sure as hell won't have any such mercy.