The problem with the theory is that the people who have a choice to avoid it just move out. The wealthy who stay can live behind gates and walls with paid protection. The people who promote these theories live in such a disconnected reality, relearning basic lessons in ways that cost societies as a whole and tragically create even more inequality and inequity than was present when they started. Now you preside over a piss-stained, violent[0] city with an eroding tax base and a widening chasm between the haves and the have-nots. Congrats.

[0] I tend to agree with another poster that the threat of violence is still violent even if the victim acquiesces to avoid violence (by not confronting, fighting back, intervening, either from direct threat of retaliation by criminal or punishment from state/society for daring to be intolerant of antisocial behavior).