This caught my attention too. A cursory search of the zsh docs don't mention functions being a type of alias. In particular:

> The registration of aliases with parameters looks pretty similar to a function definition in regular programming languages.

Well that's because it is a function definition in this programming language, no?

Furthermore, this breaks down when you, say, use `alias` to view all your aliases. It won't show the functions, because they are not aliases.