The insanity is that both NTP and unix timestamps need to be wound back during a leap second, as well as computer hardware clocks. If we just had monotonic clocks everwhere and adjusted for leap seconds in presentation then we wouldn't have many of the associated problems.

It's not like we wound back by 24 hours on leap days, that would be insanity. So in addition of leapseconds being a rare problem, it's also handled in a uniquely bad way.