@nx the markup is simple enough to explain in a few minutes. the line oriented nature of the markup makes it pretty easy to write a parser for. generally the protocol is simple enough that there are a bunch of implementations already even though the project is relatively young.
what else? i'm a big fan of client-only styles. TLS without CAs. most especially that my wife (non tech barista) was actually interested in using it.
@nx every page is a single socket request; no user tracking.
@nx the text format is simpler than markdown and i can hold all the possibilities in my head comfortably. it de emphasizes fussing with formatting. a non technical person could learn it easily and get some value out of it (administrating, organizing and updating a site could still use better tools though, but that'll come in time probably).
@nx I, personally, enjoy how restrictive it is, that it has a focus on content rather than graphics, etc.