Exposing Fundamental Primitives (was: [css-regions] Named Flows, Elements and Box Generation)

Apologies for delayed response to this thread, feel like i helped instigate
some of this discussion via other channels and then didn't show up to
participate when it came up.

Numerous WG members are of the opinion that we need to, as the Extensible
Web Manifesto says, prioritize explaining the magic and exposing the
fundamental primitives in the system.  I won't rehash the rationale for
this, but encourage you to read it for yourself and the plenty of articles
written about it.  I will note though that it explicitly states explains
how this helps us develop better high level apis - that we definitely want
them.

All of this said, what are they?  This requires some archeology and
discussion.  Alan has done a great job explaining how regions provide a
possible part of an answer, but at least a few disagree.  My question is:
is there some alternate answer that would make you happier?  Personally, i
think the named regions work is great, it makes a lot of sense to me, but
maybe there is another explanation someone has?  If so, i would love to
see/participate in the discussion as i really think that only through this
kind of change that allows us to tighten the feedback loop and
experiment/compete high level solutions can we go too much further with css
and hope for it to be palletable/understandable.