Sure, reality could be arbitrarily weird—but if the universe cannot even be approximated within a number of bits much larger than the number of neurons (or even atoms, quarks, whatever), “rationality” has lost anyway.
Why? If the universe has features that our current computers can’t approximate, maybe we could use those features to build better computers.
Why? If the universe has features that our current computers can’t approximate, maybe we could use those features to build better computers.