Someone downvoted but I want to hear your differing stance so I upvoted. (Come on fellow lemmings ` . ` let's melting-pot a little!)
Anyway -- your belief is interesting, though I feel like I might disagree! Seems similar to @Contramuffin's upbringing, but more extreme.
How would you train them beforehand? Or would you just drop them into the archetypal sink-or-swim? Don't you think the kid would feel lonely, say, if they stumbled on a jumpscare video and got the heebie-jeebies but you didn't help? Everyone makes mistakes. And outside of scarring -- what if your kid turns into one of those YouTube Kids jockeys?
Is your hypothetical "Tough shit, deal with it and get stronger" approach similar to how you were raised?
Your stance on the age-inappropriate reminds me of what @southsamurai commented! I've definitely seen a lot of "Don't protect your child too hard by concealing the inappropriate from them" lately. I wonder how many modern parents are shifting to that ideal.
You mention that there are some cases where parental controls would help, but you also mentioned that, (1) regarding inapproriacy, you shouldn't baby children and (2) regarding screen time, BananaKing's take is the best route. Doesn't that cover both aspects of where parental controls would be used? What cases would you say parental controls would help with?