If superintelligence gives you superpowers, then why isn't the world trembling at the feet of Mensa nerds? There are rapidly diminishing returns on "excess" intelligence. Life is constrained chiefly by resources. There's a baseline of intelligence needed to function in a modern society, but anything above that isn't necessarily all that advantageous.

Transport young Albert Einstein back in time to the Middle Ages? I don't think that would give you Special Relativity.