So I am not familiar with all of his books and it was some time I've read the last one (Outliers) but he doesn't give (at least not much) direct possibly harmful advice to people. He just describes some phenomena and some bold theories to explain those. It's not like you will hurt yourself committing to 10k hours of deliberate practice in your field or something.
On the other hand Oprah with her promotion of The Secret which is potentially very harmful if you start applying things it advocates or Kiyosaki with his books/mlm promotion are better candidates to put into scam category.
I mostly agree, but one thing I saw was multiple 7 year olds in my kids' kindergarten classes. They were "red shirted" by their parents because after reading Outliers they thought it would give them an advantage. I think it ended up hurting those kids because they were bored. It also hurt the youngest kids (some nearly two years younger) who were physically and mentally outmatched. And it hurt the class because the teacher had to split attention between kids who were very different in maturity and ability.
I have seen a fair bit of 'red shirting' also. It seems quite strange to me - but then I graduated high school at 17 (no skips) and many high school students in my town are 19 when they graduate now. The inevitable result of 7 year old kindergarten students I guess (btw one of my sons is 6 and in first grade).
After reading Outliers at least I have a theory of why I was a crappy hockey player with my October birthday.
It can make sense in certain situations. I personally grew up as a very late bloomer. By very late, I mean I was THE shortest person in school (boys and girls) until junior year of high school. This put me at a huge disadvantage when it came to sports even though I am naturally very athletic. This of course didn't ruin my life, and I don't think I would have ever made pro. But who knows.
On the other hand Oprah with her promotion of The Secret which is potentially very harmful if you start applying things it advocates or Kiyosaki with his books/mlm promotion are better candidates to put into scam category.