A) How has the web been around for this long and nobody has done this before, i.e. there isn't at least some kind of authoritative reference like this?
B) Having worked with many UI/layout paradigms, and full aware of the fact that none of them are very good - css is indeed perhaps the worst. It takes quite a lot of abstraction on top of it to make sense of it.
Yes - those list a bunch of values - but they don't help that much in terms of actual documentation. They list nothing but the values.
Even MDN, which is probably the closest thing to 'standard' has very few examples, missing definitions, nothing interactive.
W3C is only really the basic stuff.
Let's face it: the tool we all use for showing our stuff to the world basically has no documentation. It's a mess.
The Mac/Safari documentation is literally blank for tons of objects. I mean - $100B billion in the bank and they can't make docs. Even swift documentation is totally lacking in examples and hard to read (they're still depending on your ability to read Objective-C stuff).
To your last point, making developers lives easier does not move their bottom line is my assumption. If they improve docs it isn't going to sell one single extra Mac, so why should they bother?
A) How has the web been around for this long and nobody has done this before, i.e. there isn't at least some kind of authoritative reference like this?
B) Having worked with many UI/layout paradigms, and full aware of the fact that none of them are very good - css is indeed perhaps the worst. It takes quite a lot of abstraction on top of it to make sense of it.
But it's what we have - so good work.