Earlier quoted context omitted.
Yes, that was a design goal! It is probably technically possible to have the time continue to update with just CSS on the client (based on [1]), but the initial time still has to be set server-side. [1] https://css-tricks.com/of-course-we-can-make-a-css-only-cloc...
I'd argue this is the wrong design goal: correctness is more important. I'm in the UK but my work PC's Internet exit node is in New York due to enforced use of corporate proxies, so the time shown to me is 5 hours out. Javascript would report the correct timezone. It is not possible to correctly identify physical location from IP addresses. Not just because of proxies and VPNs and the accuracy of the data: you can go…
I missed a bus because my phone connected to Morocco and updated its clock, when I was on the beach in Spain. Weirdly it was near Málaga, not even that close.