From modern Latin therapia, from Greek therapeia ‘healing’, from therapeuein ‘minister to, treat medically’.
It makes me mad, and it should make you mad too, that so many so-called therapies are experimental, unproven ways to modify your body without any guarantee of success or, worse, with a guarantee of failure.
Too many “therapies” come from an idea that somebody dreamed of and then started applying on Guinea pigs without any kind of proper testing. Many of the diets you see becoming hits and the subject of books have not been tested. Hormone replacement “therapy” was born as a “common sense” hypothesis: top up missing hormones and you will get eternal youth. What could go wrong? That you are adding hormones to an aged body that has been accumulating mutations. The result? Cancer.
Lasers, LEDs, even plastic surgeries start this way. Eventually, some of them prove successful, many others don’t. Most are just forgotten to give way to other “therapies” somebody wishes to try on unsuspecting subjects that are even willing to pay good money to be experimented upon.
Who’s fault is it? It depends, but usually, it’s the quack selling a fake cancer cure, siphoning money while the patients, who may have been saved by standard treatment.
In skincare, the culprits often sell “FDA approved” devices. They are not. What they call FDA approval is just a loophole formality that is, by no means, a guarantee of effectiveness or even safety. You have been had.
Caveat emptor, buyer beware, especially when it comes to home skincare devices. If you experiment with your skin, be ready for failed experiments.
See also this post.