[moe]

If you have multiple levels of bullets, there’s usually something going wrong.

Nonsense. There are many situations where 2 or even more levels of hierarchy are exactly what you want. Screwing up such a common need in favor to a questionable typographic preference is not a good idea.

And yes, in theory you can "fake" the hierarchy with headlines. In practice that tends to look rather odd and make it hard to actually recognize the hierarchy. Especially in a whitespace-heavy stylesheet like this one.