Walk through the village centers of Newton, Watertown, or Wellesley – quiet suburbs just west of Boston – on a weekday afternoon and the signs are hard to miss: a Wellesley café that can’t keep staff, a storefront on Needham Street vacant for months, a Newton Centre restaurant that’s cut its hours because workers can’t afford to live nearby. Most residents don’t think of these as symptoms of a housing problem. But they are. The same person organizing against an apartment building near the train station – worried about traffic, parking, the loss of neighborhood character – is often the...