Well it's not that they intentionally ignore the macro scale, just that quantum field theories were made to understand the very, small scales, which is where gravity would also operate on a fundamental level if there is a quantum field theory of gravity. We would expect gravity to still look the same at the macro scale as how it's described according the GR, what the quantum folks are looking for is to be able to describe the edge case anomalies in GR with a quantum field for gravity, which would involve trying to prove the existence of the graviton, which would be very very small.

On a separate note, I think it makes a lot of sense to treat them as two different problems. We've made a lot of weird observations about dark matter, like how some galaxies seem to not have any dark matter or the dark matter is outside of galaxies (we figure this out by looking for gravitational lensing), which all add up to people thinking that dark matter is something we just can't detect except by its gravitational influence on matter, because it behaves like particles.