scattering in the Universe

Distant objects in the Universe look the same as nearby ones, in the sense that a redshift 8 quasar looks like a point source just the same as a nearby M dwarf star looks like a point source. This must, somehow, strongly constrain the scattering properties of the Universe. The Universe is very transparent, but there definitely is scattering and absorption (by dust, by gas, by rocks); why don't we…