There’s nothing wrong at all with “cook by numbers” and it’s especially great if you didn’t learn to cook as a child. It’s like learning at a coding boot camp where you learn to write some simple business logic based on a spec, or learning algebra in grade 8: basically syntactic transforms with no theory.
But Salt, Fat, Acid, Heat will teach you to look in the fridge when you’re hungry but unmotivated and quickly make something from what happens to be there that isn’t boring, faster and cheaper than ordering junk food delivery.
Yes you could turn into a fancy chef but the suggested advice is great for someone like me, who doesn’t really care particularly about food.