For fans of backyard ice skating, it’s discouraging enough that the winter of 2011-12 has been all but canceled. Yet when local authorities, perhaps prodded by the occasional censorious neighbor, go after owners of now-useless backyard rinks, they’re not just adding insult to would-be skaters’ injury; they’re also eroding the kind of mutual tolerance that’s needed to preserve peace and harmony in a densely settled region.