I think we all might be misunderstanding what the OP was trying to convey.

The title of the thread, "Why Overmelding is equivalent to current ATMA grinding", seems to say he is trying to compare the two systems.

But then it seems like he is instead trying to give feedback on the Atma system instead.
Such as recommending that Atma drops from Primal HM/EX fights instead of solely FATE drops... I don't know, maybe that's wrong too. I'm not all too sure what he is trying to get at.