Hm, I agree, the docs on these topics are not on the level we are used to (certain nodes missing, other things not correct and certainly a lot of context and glue missing, also more examples would be great). But to say, there's no documentation isn't correct, either.
Nodes descriptions: https://help.maxon.net/c4d/en-us/#html/60629.html?TocPath=Node%20Editor%7CIndividual%20Assets%7C_____0
Capsules: https://help.maxon.net/c4d/en-us/#html/Capsules.html?TocPath=Node%20Editor%7C_____7
In order to defend Maxon a bit, Scene Nodes mean a paradigm change. Before the documentation department had to understand C4D just like every user does, in order to document it. Now, they need a certain amount of developer/programming knowledge, in order to get the job done. Please note, I'm not saying such knowledge will be needed to use Scene Nodes (though in its current state it certainly helps), but it's needed to come up with a sensible, useful documentation and also examples. Such knowledge needs time to to build up. Whoever had to build up knowledge on a job in parallel to coping with the usual workload and delivering the usual output, maybe knows how hard and slow that can be.
But I think, Maxon is aware of these problems. And from the open positions on their site, I'd guess, by now they have also hired somebody to help in this regard. Some time ago I saw an open position in this realm, which by now is no longer offered. So, I'd expect the situation to improve.