M9 got a bum wrap with a lot of folks (including me for awhile) due to lousy magazines making them not run worth a poo in sandy conditions...when lots of them were being issued in sandy conditions. My factory Beretta mag would run with no problems. The two spares (Checkmate, IIRC) would reliably feed maybe 4 rounds before the follower stuck fast and it stopped feeding. The two spare mags were basically pez dispensers to shake cartridges in to your hand to reload your good magazine.
Perhaps that's the reason.
I would add that most things issued to Joe get a bum rap. Purdue has an entire research department dedicated to analyzing how Joe breaks and wears stuff out. Well, maybe that part isn't true. But somehow when something isn't totally Joe-proof, people hate on it.