@gwelo shamwari
Please do ask the CAA that question. They might be able to tell you why you need to know about most of the content of RNAV, several parts of GNAV, a lot of Airframes/Systems and a lot of things in Human Performance. A lot of the things you have to know for the exams won't help you at all as a pilot and are way too detailed to be of any use for pilots.
Oh and the funny thing is that some of the supposedly "correct" answers in the exams are indeed wrong. So if you apply the stuff you study you get the answer wrong. Not that you could expect to have such small issues corrected for only 69 GBP a pop (14 Exams for the ATP!!!). Oh and you only get to know the "general areas where you went wrong" as an evaluation of your exam.
If it was only the Fixed Wing questions that were still in the QB it would be easy
bye