Did the invention of the steam engine and all other heavy machines make us physically weaker? I guess so. People working on (literal) heavy stuff don't need the strength they used to.
But now they move around even more heavy stuff with machines.
I think something similar might happen to our brains. Maybe we won't be able to work ourselfs through every detail of a mathematical proof, of a software program, or a treatsie on philosophy. But we'll abe able to accomplish intellectual work that only really smart poeple could accomplish. I think this is what counts: outcome.