I think the point that Andrew is making is -
most neighborhoods grow in a natural way, not with the wholesale displacement of most of the former neighborhood population. In a situation where all the old settlers are displaced by new arrivals with money, a unbalanced segregated community, similar to a gated community, is created.
Neighborhoods have a core of people who are committed to its problems and strengths over years. It is a pragmatic, adaptive history that is passed on within the citizens of the community. It is created over generations of time and is responsive to present and past needs.
The new Willimsburg, because of a tax insentive and new zoning changes, is being formed all at once. You just has to have a lot of money, or parents who have the money, to buy in. Unfortunately often this is a marginal financial committment with very little equity and a lot of debt for the buyer.
Williamsburg, by the nature of its formatioon is a post graduate college dorm for people who need to extend their post graduate life in a sheltered environment. I do not know what neighborhood Andrew would mention as "real;" there are so many, but I would certainly suggest the upper west side, Fort Greene, Clinton Hill, Greenwich Village, Brooklyn Heights, Bed-Stuy, the Lower East Side, and on and on.
Williamsburg has been cleared, "defoliated" of the Poles, Italians, Latinos, Carribeans, Artists, hipsters etc, that have helped shape the neighborhood and made it desirable for its' diversity. Now the bland, predominantly white 20 and 30 somethings who have been overvitamined, over therapyed and over protected, have come to settle the neighborhood. This is a script for suburban living in an upscale neighborhood in Westchester, Long Island or New Jersey. The developers are the only people who stand to win unless future buyers rethink their place in NYC community life and bravely renounce the collge dorm lifestyle of a place like Williamsburg.