I mostly agree with you, but I can appreciate people wanting to fine tune a "race" gun. If all you want is a reliable shooter, it's probably better to have it slightly over gassed so that it'll cycle anything reliably.
I haven't found any reliability issues with having a tuned gas system. None of my guns are "race guns". I put 1,100 rounds through my 10.5" SBR in a single day with out a single malfunction from the gun. I had two PMAGS shit the bed and get pulled out of service but the gun didn't miss a beat. The correct gas setting is still slightly over-gased, but it's FAR less over-gased than most factory guns.