I agree that zsh's default configuration sucks (and the new-user wizard is overwhelming). I would like the project to provide a more opinionated set of defaults to OS vendors; i think we are probably just nervous about breaking 30 years' worth of expectations, and so far nobody has really pushed for it.
But i do think the misunderstanding i mentioned is very common, as illustrated by the fact that the GP seems to think that OMZ itself provides zsh's completion functionality. It's also a frequent point of confusion with people seeking assistance on zsh's IRC channel.
It's never been about 'understanding' zsh or not, it's always been about making it comfortable to use, quickly, on any given system I might use.
Sometimes a nice set of defaults is more productive than a custom solution.