Eli5: why are there multiple tectonic plates instead of just one giant one?

Question

Eli5: why are there multiple tectonic plates instead of just one giant one?

In: Earth Science

Answer 1

Currents inside the mantle are not in the same direction everywhere, in fact, that would be impossible, like wind, it’s always coming from a different direction in different places. So different parts of the earth have different forces, and some tear land apart, while other push it together, creating multiple plates that move relatively independently