Your statements, taken as a pair are contradictory; what I think we are supposed to think is that the math demands that there be a mass large enough to explain the part we do see and dark matter is what we currently call it.
And, if it exists, it can't all be balled up in one little corner to fit the current notions.
Wasn't it Faraday who said that space had to be either completely empty or completly full?
No, they are not. Whither the neutrino, before Cowen and Reines?
He was good at lab experiments and demonstrations, maybe the best ever, but he was not a theoretical physicist and had little math.