Neutrinos don't interect with EM either, so just being "dark" is not outside of well established physics. The only thing strange about "dark matter" is not that

Neutrinos don't interect with EM either, so just being "dark" is not outside of well established physics. The only thing strange about "dark matter" is not that it is dark (eg, not interacting with the electromagnetic force), but that none of the dark particles we already know about can explain the effects that we attribute to dark matter.