I have come to realise that is hard asking a question in Bitcointalk that haven't been answered before so i now just search for any thread relating to my question.
I think this thread might help Why would make the extra merkle commitment asicboost uneconomical?

I don't know if quoting this long is wrong though, since I had an experience of not been able to post a link outside Bitcointalk. I optioned to quoting.