True. "Suck it up" works in some occasions and in others it makes everything worse. It's a terrible default approach to teach your children because they can end up never learning how to deal with stress in a healthy fashion.

The result is usually someone who builds up stress where other people don't (and then acts accordingly) and who has absolutely no ability to comfort other people when they need it. Few parents want their children to be lonely assholes.

Of course it's harder to teach someone nuance. Identifying when it's okay to be vulnerable and when you need to tough it out by yourself is difficult. But if you're not capable of both you're lacking essential tools.