"Dark matter" is both the imputed matter our models tell us has to be there to match our stellar observations, and the locally-testable explanation that all this imputed matter is some freakish particle we have literally never encountered before.
The former is about as close to a scientific fact as anything gets in astronomy, while the latter is more of a "if flies hatch from eggs where are the shells" kind of thing. It'll be really significant if a "quasi local meta-particle" or whatever is found, so both excitement and skepticism are absolutely appropriate here.
I just wish pop science was a little clearer about the distinction between "this is what we see" and "this is why we think it's like that."