It's a good question and good to ask these things.
There seems to me quite strong empirical evidence that clouds of dust and gas will collapse into a disc rather than capture of material already polarised - this is from looking at galaxy and exoplanets. Galaxies like our own are very approximately flat discs and are very common, so there must be something causing that at the galactic scale. Furthermore in exoplanetary systems we have observed exoplanets in approximately the same plane - like our own solar system - which would be unlikely if it was by coincidence of extrastellar capture that our solar system was flat.