Neither of these is strictly true. Gravity is the only fundamental force that creates fields over very long intervals. (Electromagnetic forces have force carriers that can travel over long distances and times–photons–but they’re not coupled reactions that define a field of effect.) “Local” has a very specific meaning in causality (essentially, that an impetus from one system is directly coupled to a result in another system) and a more general meaning in astronomy and cosmology, i.e. it is part of an identifiable and more-or-less distinct grouping.
We know for a fact that both the distribution of mass and the signature of the cosmic microwave background are anisotropic; the former is both a cause and (presumably) an effect of the large scale structures; the latter indicates that some perturbation effects influenced the formation of the observable universe post-inflation.
Adding to Stranger On A Train’s response: Good old Doppler shift. You get a spectrum from one edge of galaxy, another from the opposite edge and the relative shifts of the spectrums tell you how fast it is rotating. (You need to do both to negate the effects of the relative motion of the galaxy in our direction.) The more edge on the galaxy is, the better. But then those are harder to get estimates on visible mass. But by sampling ones that are tilted a bit, tilted a lot, nearly square on, one can compare and get estimates of masses.
The suggestion of neutrinos as candidates for missing mass has always puzzled me. (And it’s been put forward by Astrophysicists.) The ones we are familiar with move so fast that they are virtually moving at the speed of light. (The current belief based on a chain of reasoning.) Given the energies involved, their rest mass would be fantastically small. So if the galaxies are effected by fast moving neutrinos, what keeps the neutrinos from dispersing quickly? If they are slowed down somehow, they no longer have the gravitational pull to do much of anything.
Neutrinos mostly got a lot of discussion as dark matter back before we had enough data to rule out so-called “hot dark matter”, composed of particles traveling at very high speeds. Then, too, bounds on the rest mass of the neutrino have tightened up in the past decade or so, so they also used to be a better candidate for cold dark matter. Their continued presence in the discussion is partly a relic, and partly due to the fact that, unlike any other dark matter candidate, we actually know they exist.
The referenced book covers the black hole hypothesis, and the arguments against it, in some detail. When I searched on Amazon to get a link to the book, most of what came up looked too technical (and too expensive) to interest the average reader. There is a good chance the book I referenced would be in a local library - it was in mine.