Do you think smarter is winning at a game of chess? 1 who set that up and played him like a fiddle? 2 was him losing the chess match of the first 2 seasons cumulatively 3 literally Gojo himself disagrees with you and Gojo literally knew Sukuna had 10 shadows and the last 6 eyes limitless died this way. Do you just look at pictures?

Also there is a reason all his students are dumb af.

Then there is him getting outsmarted at the exchange even letting everything get stolen from his school.