Sometimes people don't try hard if there is no fear of failure. Removing the key labels makes it harder to cheat and forces you to do it the right way. Some people will rationalize in their head ("oh it's just this one email I am typing, I am so far behind I can't afford to be slowed down"). I can see this method being effective by "forcing" people to learn to touch type.
uh, I think you are putting the wrong slant on things, like people are cheating losers.
I have been touch typing for years, but I probably look at my keyboard from time to time and do not know I do it.
If you asked me where the B key is, I would have to look. If you asked me to type banana I would do it without looking.
I have caught myself looking, like a passenger in my own body, maybe to orient myself when crooked, I'm not sure. But typing is so automatic that my conscious brain is not even involved in the process.
Same effect - but with less sanding.
With that said... there are a few good resources out there that probably weren't there (or I didn't find) the last time I looked.
I ended up just spending extra for a DASKeyboard sans writing... but may still "convert" some of my other keyboards at some point (going to build a new house and I'll have a work room when it's up)