[colllectorof]

That's assuming that those companies want outside developers to be knowledgeable. That's a questionable assumption. If anyone here remembers how old Microsoft used to operate and why people went to get MS-something certificates you know what I mean.

"Free" documentation is often designed to give you barely enough info to start using their products, but not much more. And we're kind of used to this by now. MDN, FreeBSD hanbook or the original set of Smalltalk books stand as exceptions and reminders what things could look like if motivations were different.