Google's proposal is a smear. [1] Most time servers do not use smear. No idea what behavior it may introduce in places where sub-second time is important. Curious if all these bugs [2] were fixed specifically to deal with going backwards.
The brilliant thing about the smear is that it distributes the new second across each second of the day, so that each second differed by 1/86400 seconds, well within the margin of error for NTP.
As far as the computers were concerned, nothing was different.
I don't think we can predict ahead of time whether we'll need a leap second or not
If the question is "why bother syncing time to Earth's orbit around the sun at all", I don't have a good answer for that except at this point, it's tradition.
[1] - https://developers.google.com/time/smear
[2] - https://rivassec.com/leap-second-chaos-2012.html
As far as the computers were concerned, nothing was different.
By any other standard, most manually set clocks are up to a full minute off all the time.
MiFID 2 alone forces sub-μs precision. Million times less than the leap 1 second.
NTP minute away is good for displaying date on the workstation, not for many of the devices that are critical to the modern world.
Sure they have their own time servers fed from the GPS, but they need to be _accurate_ in relation to the world.
But timestamps used by companies forced to use very accurate timing must be synchronised to UTC.
If the question is "why bother syncing time to Earth's orbit around the sun at all", I don't have a good answer for that except at this point, it's tradition.