My recollection of what Neal DeGrasse Tyson said on one of his podcasts is that matter we cannot see wouldn't explain the "missing mass" because experiments indicate that "dark matter" does not interact with normal matter or photons, except in the form of gravity. I had thought for some time, "perhaps dark matter is just matter for which we have no evidence of its existence because we cannot see it." A hidden black hole would fit the bill there. But what was said on the show completely dispelled that notion. The problem here is that I am a non-scientist and don't quite recall what he said in the episode. Real scientists with knowledge of this--please weigh in!
As a footnote--Wikipedia says that a small portion of "dark matter" seems to be just regular matter we cannot see, but mostly it seems to not fit the characteristics of regular matter.
Follow-up question--could a huge number of supermassive black holes cause the effects we see from earth? My reasoning suggests the answer would be "no." The thought process being that, if scientists have been theorizing a larger number of supermassive black holes for some time and also wondering what this "dark matter" stuff is, more of those scientists would have said, "perhaps dark matter consists of those theorized black holes we haven't seen." I think this hasn't happened because scientists who actually know this stuff (not me) had already concluded that black holes don't fit the mugshot.