It still does not answer my question "Why" although I have just realized that HN is someone else's idea and they structured it they way they wanted, not the way "I" would like it to be.
If someone finds it beneficial, then fine. The only thing I am concerned is that if I wanted to apply to YC I'd need be active here. And if that is what motivates users to post here then they'd post just anything to get noticed. Anything is not good. Good quality information is good. As a startup founder I value time more than anything hence I'd rather spend time working on my product than on trying to get noticed on HN or brush through so many articles (of different value). But it's just me. Maybe I am wrong....