it only hurts while they're doing the scraping and poking, plus a couple of hours after that.

Obviously, your family has higher pain tolerance than mine. When I *did* go regularly, I still experienced pain for ~24 hours after a cleaning; that hasn't changed.

Much of preventative dental care is for the benefit of your gums

Makes sense in principle. But given how much abuse my gums take during a "cleaning", I am skeptical about their methodology.