His solution turns out to be close to OAuth 2.0 in the end, so you are right. But I liked the article because it walks you through the thought process of someone trying to do it on their own. This understanding of all the small things you may end up ignoring in your own efforts actually makes a stronger case for OAuth then believing an expert's words.

Actually, it was basically 2-Legged OAuth 1. I was shaking my head all the way through the article, having gone through the same process about a year and a half ago.

We (developers) do love re-inventing wheels.

When I need to learn about a wheel, I usually attempt to re-invent it. But in practice (production), I tend to choose a wheel that someone else has already spent years making perfectly round.

What is learned from re-inventing definitely provides unique insight into how the better wheels are actually spinning and ultimately helps us make better use of it.

Do you have any recommended tutorials/walkthroughs for building a REST API?

I'm not saying that we should all use OAuth 2.0 without due understanding, but we should all admit that we're not all experts at everything, and sometimes we should bow to peer reviewed knowledge.