I don't sign up to be a referee, so I generally don't pay any attention to the other people on my card. I call what I see, but I'm not going out of my way to watch what you do like a referee would. While you are foot-faulting in the fairway I'm at my lie looking at my shot; I really don't give a flying what you are doing. As a result all I generally see is people stepping off the tee or stance violations around the basket, and I call those. Usually when somebody on my card calls something other than those things I can't second because I honestly wasn't watching.
I guess I'm also disagreeing with that big time, especially if we're talking about sanctioned events. I do believe there's still a requirement that you be a certified official in order to even participate in tournaments at a certain level. So not only are we signing up to be a referee, we are actually paying the PDGA to be one.
Should and have to are two different things. I'm not paying money to work, I'm paying to enjoy some disc golf. If I wanted to play referee I should get paid for it (or pay nothing at all), not the other way around. So if I don't see something egregious I'm not calling it.
Again, not staring down like a ref, but paying enough attention that it's still fair play. Haven't you ever played pickup basketball? Or any other self-officiated sport? It's kinda unrealistic to assume that "I'm not paying attention and I'm not calling anything unless it's egregious" and "fair play for all" are compatible in a self-officiated sport.