Basically the issues the military had in Vietnam with the M16 still largely exist with the AR-15 and other ARs.
They need to be kept remarkably clean. Maintenance is a pain in the butt. They don’t do a hell of a lot of damage and the bullets can travel a ridiculous distance. If you are going to get an AR get it in .308 or some other caliber. .223 is crap.
I can bury my Siaga in mud for a month, pull it out, slap a magazine in it and shoot it. Try that with an AR.
I’ve had my Ruger 556 since 2011.
I am notoriously bad about cleaning after I shoot.
According to my records, I have put 2,800 rounds of Federal .223 through that carbine since I last cleaned it.
It works every time. Stop trying to make me feel guilty about it!