Poorly phrased. The most recent stars are on the edges. The inner stars were first, hence the “working outwards”.
Or did ie dark matter/energy somehow coalesce on the outer edge later? Milky way is supposed to be very old place, almost as old as universe itself so one would expect more homogeneous distribution, at least as a layperson.
It seems that you need quite large concentrations(as in scale of whole universe average) to actually get to star formation. Otherwise stars would be uniform trough the universe.
Then again I am not astronomer.
The pre-stellar cloud has the same mass, and thus the same gravitational impact, as the stars that form from it.
Aren't fluids (such as a hydrogen gas cloud) densest at the bottom of a gravity well? It would be expected that the nearer one is to the galactic center, the denser the intergalactic medium would be.