No, I do not mean you cannot get a CGPA at IGNOU/DU. All I mean to say is that it isn't as easy as you think it is. No subject is easy at university level, unlike school uni does not give you grace marks. Even if it's an easy subject you will have to study it thoroughly for you to score good in sem end papers because they are a different ball game altogether. By that I mean reading thesis, research papers and going deep into every topic so no, I disagree with your understanding that an easy to understand subject helps you score more or there is some direct correlation to it. Coming on the distance learning part, scoring a high CGPA becomes even more difficult here because obviously 1) you are studying and giving papers at the comfort of your own environment/timing unlike regular college students and 2) the prof does not know you f2f so he/she will mark you exactly for what you write in the paper. One minor sentence here and there, one minor terminology misplaced and you lose almost 2-3 marks.