I think all of the topics are best understood in terms of three groups: classic classes, new-style classes, and roll your own classes. Lumping the latter two together won't help one bit.
While that's technically true, most of the idiomatic uses of
[Aahz] metaclasses
that I've seen *do* result in the creation of "normal" new-style classes. We don't want to obscure that, either, IMO.
Okay, I've added a paragraph to the descriptor guide: """ The details above show that the mechanism for descriptors is embedded in the __getattribute__() methods for object, type, and super. Classes inherit this machinery when they derive from object or if they have a meta-class providing similar functionality. Likewise, classes can turn-off descriptor invocation by overriding __getattribute__(). """ Raymond Hettinger