Back to the OP, I tend to agree.
The PC is great for starting out. It's really tough to do damage with it. About the worst you can do is nothing...working polishes with the PC takes a very long time.
From what I've read on the forums, and from my own experience, the most common problem with using the PC is not working the polishes in for an appropriate amount of time. It can take ALOT of time and patience to get significant swirls/marring out with the PC. That was the learning curve for me. I didn't realize I had to sit there on a particular panel for so long, then repeat indefinitely until I acheived the results I desired.
But I'm glad I spent all of that time on the PC before moving on to a rotary. The PC allows for mistakes that the rotary doesn't. It was a GREAT learning tool that does produce results, albeit with some extra effort.
I still use the PC for tight spots, for relatively unmarred finishes, or bodywork areas that are too delicate for the rotary (high spots, edges). But I find it very tough to go back to the PC knowing how much more efficient the rotary is - in both speed and quality of the final finish.