In Harry Potter for example, I hated the idea that magical people could help with so many real-world problems. They just choose to stay exclusive.

Harry Potter is the absolute worst about this, because seemingly there’s no real limit on magic and it’s abilities. There’s no pool of magic energy to deplete, it’s not a scarce resource in anyway, the only reason they don’t share is because they just don’t feel like it.

I think FMA handles it pretty well actually. A lot of the information is available as long as you’re willing to study complicated chemistry and physics to be able to do it, and most of the actual secrecy is specific to the military. Atomic theory is public, blueprints for how to build an atom bomb are secret.