In the popular accounts of dark matter than I’ve read and seen, black holes are often mentioned as possible explanations, but quickly dismissed without any ado, tossed into the reject bin along with neutrinos, dust clouds and such. Casual rejections like that are often signs of sloppy science, and fresh opportunities for good science.
Science has become a lot like government contracting.
Obvious, cheap solutions are rejected for Rube Goldberg complicated theories that require years of research effort (and funding).
It’s good for business, at least the business of researchers and theoreticians.