> HN tends to be a younger crowd whose peers cycled through a number of social-networking and messaging apps as popularity waxed and waned. But older generations

What is your definition of younger and older? Anybody born in the 70s or later experienced an ongoing procession of instant messaging choices. I would tell you it is precisely that experience that informs my apathy towards the latest and greatest Hot Thing, and makes me appreciate boring old SMS (and by extension, iMessage) that I know will just work with anyone I meet.