I wouldn't say they are 'stupid', mus.
I would say that many times, when studies come out that pronounce "Drinking lots of water is healthy", most people cheer and say "I want to be healthy!" And then, immediately, everyone is consumed with guilt, knowing they aren't going to follow through.
As for shaving legs bringing back thicker hair? Since when was that a 'medical myth'? I'll give it old wive's tale status, but I've dare say we've never seen the Harvard Medical Review do a study on leg hair regrowth. Preposterous!