May I suggest that we have people with PPLs, who should not have them, as they have never really learned to fly.
At the risk of using slightly artificial language, I think many flying schools teach people to operate an aeroplane rather than really fly it. Mine did, and I don't think it's really such a bad thing (although I agree that departing too far from the POH is stupid). Remember that the average PPL will probably fly a dozen hours in spamcans over one summer, and then let the licence lapse after the first spell of bad weather takes them outside club currency rules. I'll be sunny days only from licenced airfields, nothing too demanding, and learning a set of rules about how to do it is fine.
Those that keep using the licence can start learning how to really fly an aeroplane - the old "licence to learn" cliché. If I compare myself against someone who really knows how to fly my aeroplane, then there is no doubt that i've got a long way to go, but i'm learning. If I had stuck with PA28s then I would probably still be flying for the most part in the way I was taught. Quite safely too.