Fetching time in the browser isn't accurate because a lot of trackers exploit timing in order to fingerprint users. A lot of browsers now purposefully reduce the precision of the clock. See:
Oh, how convenient. Sometimes I wonder if we shouldn't find a way to be able to run trusted applications instead of making everyone's life difficult all the time, and that's speaking as a security consultant, not even a developer... but yeah I don't see a good way to make that happen.