This particular kind of mindset seems to be buoyed by that stereotypical boomer mindset of 'when men were still men', and that crying or going to therapy is for pussies. The same goes for the notion of physically disciplining kids.
Bullying isn't a 'necessary' evil, people tend to conflate that with the importance of building resilience in young people. You can get tough without being ostracized and traumatized by your peers. Thinking that bullying kids is beneficial to them to combat obesity is just grotesquely ignorant and goes directly against any medical or pedagogic stance on the matter, no matter how many personal anecdotes the suggesting party can ham up.