Why? The only difference was that white flight had a quantifiable cost barrier preventing minorities from leaving decaying inner cities as well. She's saying that this is disturbing because it's still happening, even without that financial barrier.
What if I reject the premise? I've yet to see a compelling argument as to why this type of self-selection is truly harmful. Why is it a problem if folks of similar culture choose to utilize the same tools? This idea that we should all live in close exposure to diverse opinion is nice, but goes against my basic instinct. I don't want to spend my time defending my cultural choices to folks who disagree. I don't need my life to look like an internet message board.