Of course parts of those neighborhoods were terrible -- it's difficult to argue that 6th and Mission isn't better now than it was 10 or 15 years ago -- but to define entire neighborhoods by those types of intersections would be wrong. 16th and Mission was -- and honestly, still is -- often overrun with drug dealers and prostitutes, but if you were to have walked two blocks in any direction back then you would have passed countless independent art galleries, rehearsal spaces, and performance studios, not to mention an even greater number of family owned restaurants, grocery stores and shops.
And the best thing about all of these places was their accessibility: nearly anyone could afford to go out to dinner or an art opening, see a band play, or just have a couple drinks down the street from their house. It's that accessibility that's missing now: working class families, artists, and musicians can't afford the neighborhoods they helped build, so slowly, through Ellis Act evictions or sheer frustration, they start to trickle out of the city, taking with them what made the area desirable in the first place.