It’d be nice to have better docs, but it’s not especially in scope for browser docs. Instead, someone should point to some good basic resources about linear algebra: matrix math, homogeneous coordinates, eigenvectors and eigenvalues, etc.
This particular blog post doesn’t really say much.
Homogeneous coordinates are not linear algebra. Translation is simple, but few people actually understand how the perspective transformation works - it's a convenient hack but if you try to figure it out from scratch you may be surprised by what's going on.