Why are scientists obsessed with finding the most exotic explanation of Dark Matter without first exhausting the more prosaic explanations? It is Occam's Razor upside down.
I think that the reason is there there is a Nobel Prize and fame if Dark Matter turns out to be a particle, but there is no glory if it turns out to be something more ordinary such as neutral hydrogen, dust, etc. Even a modification of Newtonian laws at a distance to explain Dark Matter is not exotic enough.....so we have to endure Crackpot Cosmology Theory (CCT) of the week from here to eternity...