As a professional programmer myself I can say that yes, linking to the pdf on the help menu is not a difficult task, but that’s not really the issue. They’re obviously trying to get away from generating pdf documents and want to steer users towards online help.
Online help has its advantages. If you need to make a change to the documentation, you change the website and everyone automatically gets the new information rather than having to generate a new pdf and make it available for download. And of course, all corporate executives know that being “in the cloud” is trendy and thus marketable.
I personally prefer a pdf for documentation, and there’s also the issue many have where they intentionally keep their studio computers disconnected from the Internet. That said, when a company makes a change like this (making it difficult for you to not do it their way, e.g. having to hunt down and download the pdf), it’s usually an indication of where they’re going whether you like it or not. My crystal ball sees a future version of Cubase where there’s no pdf documentation available at all.