Dark matter is not an explanation, it's a placeholder. What we've observed is a gravitational pull we can't explain, to which there are three possible explanations:
Thank SwanClipper the Great someone here who understands!
It gets frustrating that every time we find something new, people trot out the old "So there's the dark matter!" As if finding our Oort cloud explains the anomalies over the whole universe. Or these low luminescence galaxies for that matter. As I've said before, I wish "it' had never been named "dark matter".