Fetish.

Programmers tend towards the same behavior: if you've ever read through an over-engineered solution, you can tell it came from a person or team that privileged the technology over the solution. So it's a kind of technological fetish.

Same goes with visual design. "Want to see a site about reverse engineering? Well here's a giant animated triangle for you, gliding across the page like a fish. See what we did there, isn't that neat?"

I just closed it instantly because it didn't have a JS-free fallback of any kind and I run NoScript. As usual, turned out to be the right decision.

Agreed. This is exactly how a guide should not be like. Contentwise I think it's good so far.

Given that it's someone's labour of love, they are allowed to do what seems like over-engineering to you, if they want to.

They have the right, yes. But they'll still suffer the consequence of exercising that right, however, in lost readership.

why not? it's working properly and it's better structured

Not on Firefox mobile it works but elements do not feel like they display right. And you can scroll down to see hover answers, which had no questions.

I found out what those were exactly since I jumped into desktop mode, which had even more noticeable issues.

I hate mobile first design choices for adaptive interfaces, since they in a lot of cases, aren't suited for either platform

Most of the UI animations are laggy in my browser (Firefox 60).

It's not working properly at all! [1]

[1] https://imgur.com/a/xHGq2Gb

Very slow and laggy on my phone.