Why is plate tectonic theory considered to be a unifying theory?

Question

Why is plate tectonic theory considered to be a unifying theory?

Answer 1

It explains many phenomena.  It explains mountains, deep sea trenches, volcanoes, earthquakes and much more.

Answer 2

Plate tectonics, in one way or another, explains over 90% of all geological processes on Earth. Even more complicated processes has its roots in plate tectonics.

Answer 3

Because it explains everything we see at least geologically here on Earth.