The reasoning might be that if a place gets luxury apartments, rich people will flood the area. Then the crime rate per capita goes down. The criminal population becomes diluted. It starts a snowball effect where crappy apartments in the area looks more and more attractive to the upper middle class as more upper middle class outbid previous poorer renters for the old housing.
I know that's the argument, but it doesn't make much sense to me. It's comparing to a fictitious alternative where rich people don't move in. Why wouldn't they? It's already a desirable place to live, so rich people desire it too, and by definition they can afford to act on that desire.
It is not hard for a rich person to outbid a poorer renter. I mean, this doesn't require a complicated explanation. Whether or not there's new housing, rich people can already outbid current renters because they have more money.
And when this happens without new housing, not only does a rich person move in, someone else moves out. By trying to prevent gentrification from indirectly causing displacement, you just cause the displacement right away.
This still sounds like supply and demand doing what one would expect, not doing the opposite.
