An analogy:

Imagine that half of the labor force makes cars, the other half creates software. The average person buys 1 car and 1 software per year. There's a breakthrough, AI can now be used to create software almost for free. It can even make 2x more software per year. The programmers switch to making cars. So now the economy is producing 2 cars and 2 softwares per worker per year! Salaries have now doubled thanks to technological progress.

You could argue that this will increase inequality and all of the productivity gains will go to the top 1%. I don't think so.