because websites are sometimes interactive and allow the user to schedule things to happen at certain times.
And displaying time/date locally would leak that information anyway if you wanted to do it in a way that works in various contexts it would need to in a website (e.g. canvas based apps)
even if you just let the user stylize the font of the date (which you clearly would need to), you tell your magic date input to only show the current hour, then use a font that has a certain width for each number, allowing you to then based on the width of that element figure out the hour, same for other things, obviously. It's easy to imagine some thing like that without thinking about all the details, but it's not really feasible once you think about how this would be implemented and how it could be circumvented. And that's in addition to not working in contexts where you schedule a blog post, zoom meeting, or whatever else might require the server to account for user time zone
And displaying time/date locally would leak that information anyway if you wanted to do it in a way that works in various contexts it would need to in a website (e.g. canvas based apps)
even if you just let the user stylize the font of the date (which you clearly would need to), you tell your magic date input to only show the current hour, then use a font that has a certain width for each number, allowing you to then based on the width of that element figure out the hour, same for other things, obviously. It's easy to imagine some thing like that without thinking about all the details, but it's not really feasible once you think about how this would be implemented and how it could be circumvented. And that's in addition to not working in contexts where you schedule a blog post, zoom meeting, or whatever else might require the server to account for user time zone