All companies make mistakes.
Also Iíve been seeing Daniel defense guns slipping out of the factory without the castle nuts staked. That bothers me.
BCM had some 14.5" ML that had the wrong gas port diameter, and recently their bolt carriers look like they were milled by a band saw.
LMT had the issue with the NZ bolts.
KAC shipped a few of the first MOD 2 lowers (no longer have QD ports built in) with the trigger guard ears not properly milled. Cut enough fingers that it made the internet rounds.
Noveske had a batch of barrels slip out with non-concentrically threaded muzzles.
HOWEVER, each company quickly noticed someone was falling down on the job and took care of the problem.
With regards to DD ...
They let some guns out without the handguard screws locktited. People complained that the handguards loosened. That was an easy home fix. My personal issue is their use of a polymer dust cover. I hate them. Also, just install a $7 MagPul trigger guard instead of that stupid grip / guard combo. The grip is fine, but I had the attached trigger guard.
Daniel Defense guns are FAR more refined than BCM. I've owned enough of both to intone a strong "refinement" preference for DD.
To my mind, BCM has replaced Colt as the "working standard". From there you step up in refinement and innovation.