I think it's the same with any large application and pretty much any operating system. Even the ones that are well documented still present the problem that you need to find the relevant bit of the documentation and when you have found it you often then need to search for another bit of documentation.
And whether you find it or not can often depend on the exact search term you use.
I think Sonar is one of the better documented applications, but I've certainly spent an hour or more trying to track something down in the help/manual before now. At least the information's usually there somewhere - the model of how not to do things was Windows 95 where the help troubleshooters consisted largely of "reboot" and if that didn't work then told you to "ask your systems administrator for assistance". But I am my systems administrator.....