Great post, Cpu_Modern!
Do people want to spend all day following a schedule? Doesn't sound like my ideal life. One may need to follow a schedule at times and for certain things, certainly, but I sure wouldn't want to live a life of constant clock-checking.
I suspect that scheduling is a necessary step on the road to higher-level functioning. I know I tried scheduling for a while, which helped me a lot compared to what I was doing before that. But the more I "get" GTD, the less I need a schedule, and the more effectively I can work.