There is a distinction between needing a way to synchronize, and needing accurate timekeeping.

GPS needs accuracy. The satellites are moving many kilometers per second and so to know where they are (and this where you are) you need to know the exact time a signal was sent, and then that pulse is synchronized across the globe.

It is a rather unique application. Lots of other applications need a global source to synchronize but are less sensitive to errors in that source.

For example you need to sync power across a large network to avoid blowing out transformers, but you have a rather wide acceptable variation in the frequency with which you can synchronize that network. For instance the Texas network ran at 59.4Hz during the 2021 blackouts without failing.