Sorry for not replying before - not sure if I received a notification.
Essentially, there was a decision taken at one point to merge the Reference and User guide simply because there was a whole lot of duplication, and it was extremely difficult to find methods to link between those two guides (especially adding to the fact that we now maintain multiple versions and different licences in some products, making hardcoded links impossible).
Furthermore, we also took the decision to separate the "What does this do" (documentation) from the "What can I do with it" (training). The first result was a somewhat reduced documentation size, the second one was more complete training material. Of course, nothing is perfect and we consantly try to improve both parts, but it would simply be a massive challenge to have all the information at the same place - there is no single tool that really achieves this well (reference, videos, training material, exercises, feedback, resources, etc etc).
So basically what I'm saying is, while I do wish we could have documentation that contains everything you need to know about the software, the reality is, documentation and training go hand in hand and you can't understand the whole of the software without using both.
As for the resource section, that will soon be replaced by a centralized resource center which will be removed from the main website, which will simplify things greatly...
Hope this helps,