People are wrongly advised that they can go out and make a fortune after a short course, which is rubbish. The NVQ was (is) okay if it is used as part of an "on-the-job" training program over a couple of years. The problem is that other private providers have been allowed to hijack the system and sell the courses which are not fit for purpose (and not what they were intended or designed for).
For my part (I did one of the courses) I know I can't make a fortune from a being a jobbing plumber, too slow and not enough knowledge, and I probably never will have. The difference is that I (and many others) will sacrifice that fortune and do a good job. Yes that may mean I have to go and chat to more experienced people (sometimes on here), but the important thing is that the job is done properly. The problem is with people who just want to make the money and don't really care if the job is done correctly, just do it the quickest way possible, take the money and run. That has nothing to do skill or competance, that is about character, honesty and self-respect. There is no qualification for that.