No, this applies universally, and I very much subscribe to that myself. And to prove that point, I have spent considerable amounts of money on original artwork from otherwise unknown artists, simply because I love their work.
Back to the original argument of charging at least the minimum national wage per hour: This was simply meant as a starting point. I personally aim at around £25/hour (for retail pricing), with artistic value added on top. I know some production turners who will charge around £35-40 per hour, and that about matches out in the end, because they are about 50% faster than I am (in order to achieve the same quality). However, if you go to a point where you don't charge at all, then as the hobbyist doing that you can spend an infinite amount of time on the quality and still beat hell out of any competition. You are basically eliminating competition, and that's where things get problematic.
I don't think any professional has a problem with competition, they will find their niche and get good at it, and then produce a level of quality that commands a certain price, and if others want to get in they'll soon find out that in order to get the same quality they have to spend the same or more time, and things sort of level out. However, by not charging for your time, the whole thing goes completely off the rails, and essentially the only hope for us (charging turners) is that eventually you run out of time, since that is the only limiting factor for you.