Reconciling QFT with chemistry?

For background, I am not very mathematically sophisticated with QFT, but have been trying to get a conceptual grounding. In his Biggest Ideas series, Sean Carroll discusses the idea that in QFT there is a superposition of any number of particles in any region of space.

This seems strange to me given that before QFT we were content with the laws of chemistry which rely on a stable number of electrons orbiting atoms. How can we make sense of these laws of chemistry if the number of electrons could really be any number at all if we were to look.