I have a couple more thoughts before letting this thread go(and, yes, I've said it all before, and probably better)--

Harmony singing is a social activity, and, though it is a much loved one, it has gone by the wayside, and been forgotten by most folks. In the once-upon-a-time not-that-long-ago, there were Glee Clubs and Singing Societies and Community Choruses, as well as the barroom crooners of the Pious Friends variety. Families used to sing together, unabashedly and even enthusiastically--now, the only place people sing together is in church--

The temptation is to say that, like many other things, people just don't have time for it, but I think there is more to it--Harmony singing is based on co-operation, and the first thought is, "What can we all do together?" That's an idea that runs counter to the prevailing popular philosophy of "I want total freedom to do what I want, where I want, and how I want."

Artful Dodger asks, "Why do we have no a cappella small-group tradition that caters to a real diversity of music: madrigals, glees, art songs, minstrel songs, folk songs, barbershop, ragtime/novelty, swing, doo-wop, jazz, pop.."

While it is true that there are some groups that can do that, when you demand that of everyone, you really set a barrier--because if everyone can't do everything, then no one can do anything--