> The implication I'm picking up on is that the blight that has continued/worsened since I've left is somehow, inexplicably, my fault for not sticking around. Please, explain how that is or is not the case.IMO comes down to the economics of how a city operates. The city needs money to provide services. The people need money to afford to patronize businesses, keep up their properties, and keep their city government afloat. Businesses need paying customers, and employees.
If you don't stick around, you can't contribute to any of that, other than if you were perhaps a business owner. But then if the people working there aren't from there, or if the owner moves the money out of the city, it can still provide no net benefit.
Try not to take it personally, but yes, moving away does not help and may even do the opposite of helping. But maybe if you stayed you would have ended up worse off and dragged the whole thing down? Can't say for sure, but it is obvious, and widely accepted by academics, that in the general case, white people leaving hurt black communities more than it helped.
There's also the social aspect of which people that make up the community to consider. The less homogeneous the community, the more difficult it is for people to empathize with and help people different than them, which perpetuates systemic racism and inequality, etc.