Very few (almost zero) digital systems need atomic time.

They need a coordinated time, but it need not be atomic.

Their ideal time is one with exactly 86400 seconds in a day, and each second being equal within the natural variation when measured by the quartz crystal in the system clock

That variation is relatively enormous and provides a wide range for how long a day could actually be according to a more accurate atomic clock.

The challenge is how to bootstrap a coordinated time across the worldwide network of computers without it being atomic time.

But almost no computer programs care if a second is long or short by a few parts per million. If they did they would already be exhibiting bugs on commodity hardware.