That's honestly why I don't get the kvetching/confusion. Clearly, there is more information to come about eligibility. But the idea itself is not bad, and I think folks who are feigning great confusion about the intention beyond that aren't thinking about it practically.
In most cases, it is obvious what category most films will fall under. Sure they may be outliers - and who knows, yes, maybe one film will indeed win both awards one year. I just see this is as sort of a take on what the music industry has always been like.
This is also clearly a response to pressure for the academy to "diversify" - both in terms of identity politics and audience share. It gives them a world where they can give an award to both Moonlight and La-La-Land.
The more I think about it, the more it is a good idea IMO. I mean, when you look back at the entire history of Best Picture winners, the Academy hasn't done so hot in actually picking the creme of the crop, particularly for the winner. When you look at each year and the films that have become representative of their respective eras, compared to who swept awards, they often haven't done a great job, at all. This helps them hedge their bets better, having recognized a wider variety of pictures.