Those mostly seem the standard Ruby/Jekyll/GitHub Pages setup instructions?

I don't love how bundler works by the way; I think it should/could be a lot better in many different ways. Same for Jekyll. But once it works, it generally keeps working.

I don't think Jekyll (or Ruby) are a paragon of stability. I'm sure some stuff has broken over the years. It just seems to break a lot less than the JS/Node ecosystems.