We have to do better at finding a way to teach this stuff.
https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotati...
IME, that's not at all true; most of the theory-heavy sources I've seen are explicitly framed as alternatives to the large body of intuitionist tutorials that avoid theory almost entirely, focusing on a few popular applications (usually, collections and IO.)
"In mathematics, the quaternions are a number system that extends the complex numbers."
Naturals are a subset of integers. Integers are a subset of rationals. Rational are a subset of reals. Reals are a subset of complex numbers. The latter are a subset of quaternions. It's not difficult to construct each number system. If you look inside any undergrad math textbook, you'll find exact same writing style showcased in the Wikipedia article on quaternions.