From TFA:

"Unfortunately, no matter how hard you try, there is a certain percentage of nodes for whom hole punching will never work. This is because their NAT behaves in an unpredictable way. While most NATs are well-behaved, some aren’t. This is one of the sad facts of life that network engineers have to deal with."

In this scenario, the article goes on to describe a convention relay-based approach.

I would guess that most consumer routers are very cooperative as far as hole punching because it's pretty critical functionality for bittorrent and many online games. Corporate firewalls wouldn't be as motivated to care about those use-cases or may want to actively block them.

> Corporate firewalls wouldn't be as motivated

I think parents point is a bit like "you can't disallow lock picking"; the term "hole punching" being used to describe techniques that are intentionally trying to bypass whatever thing others (particularly corporations) try to put in the way, sometimes for good reasons and sometimes for kind of shit reasons.