Also: aerodynamics is not really hard, anyone can fold paper planes! Or: programming 3D games is easy, just build new levels for an old game! Or: I don't know what I am doing here, but look, this photoshop effect looks really cool on my holiday photos!

etc.

Seriously: The writer would not be able to write anything about K-Means if not for people looking at it from a mathematical view point. This angle is of tremendous importance if you want to know how your algorithm behaves in corner cases.

This does not suffice, if you have an actual application (e.g. a recommendation or a hand tracking or an object recognition engine). These need to work as good as you can make it because every improvement of it will result in $$$.