It’s a big deal for harry potter fans cause it fixes the Books. Draco was supposed to be a rival to harry that had a redemption arch that in the end turns on Voldemort. But it fell flat on his face.

Harry also just randomly fell in love with a girl that had no chemistry with him making it really bitter. Malfoid fixes all books and fixes all plot holes created by Draco.

The general consensus I can find on what defines a galaxy is "Most astronomers agree on these basics: galaxies are massive, gravitationally bound systems of stars, gas and dust, with an important but poorly understood complement of dark matter. " and it’s not agreed because even with the measurements we have some that lack dark matter. So it is a good and open question even current theory lacks

As far as I can find the theory is more the universe forming without Dark Energy or matter being around it, it does not discard them existing in some other way but it disproves it’s all around us making a lot of things happen just with time. I think in one of the articless the guy just says it. It dosen’t mean it dosen’t exist.