Einstein seems smarter because he was smarter. He didn't transform one small area of physics, he solved a lot of problems that were out at the edges and introduced new ideas that made them tractable.

Of course other people helped, and some of those other people might have created GR eventually.

But he was the only one to pull it all together.

In physics now there are plenty of people with world-class math talent, but no one with Einstein's intuition, insight, and creativity.

Which is why I think progress on the really hard problems has become glacial. Those problems always need deep creative insight, and math alone isn't enough.