Even when using an NTP server to set your time, network latencies have to be taken into account. Otherwise, if the request took 300ms round-trip and that weren't accounted for then your machine is already 300ms off from "official" time. Depending upon what you're doing, being that far off can be critical.
These are things your dollar-store quartz watch simply doesn't need to concern itself with.
If you have a critical need for leap second time you're typically using your own means of NTP and not Microsofts broken ass bullshit.
I love that statement! It reflects my 40 years experience in software - if you're doing something serious then don't use Microsoft's broken ass bullshit. I smile and remember Microsoft's origins as a gaming company. To this day that's what they're best for!
Does it? My system/bios time is in UTC. The timezone is not managed for me, when I travel I change it. DST and leap seconds are deltas you add to UNIX epoch. Tracking the number of ticks since epoch is a simpler task, much closer to what a quartz watch attempts to do on its own. Both fail when the battery does, of course.
If your end user facing application can't handle 300ms drift that seems like a bug in the application. Even stuff like TOTP generators let you apply a time delta correction and servers usually allow >1 minute drift.
If your quartz watch battery goes flat you replace it straight away because a watch with a flat battery is 100% useless. But if the battery on your motherboard goes flat you don't even notice, so why would you replace it? To a layperson, "my computer's time is always wrong" is not likely to be caused by a random flat battery that they didn't know existed.
Microsoft came up with this "Secure Time" system so that even computers with flat batteries would be able to work out what time it is, but obviously it is kind of weird and sometimes makes wrong decisions.
There are longer life batteries, but they're _expensive_, e.g. a Tadiran TL-4934, 1Ah, with a shelf life of 40 years will cost ~5$ in bulk.
"Microsoft came up with an internet boot image that allows your computers to boot windows even if the hard drive is dead without users realizing this is the case"
Honestly, when the battery dies, it's time to take it to the shop.
This shouldn't be overkill for a server dedicated to timekeeping on a large company network, right?
In a datacenter one could even go for a matchbox sized atomic clock. Last I checked (years ago) such a miracle device could be had for ~$1500.
Then: how often does atomic clock (or even TXCO) fail, in practice? My guess: only about as often as even the backup power fails.
Note that either should provide accurate timekeeping without even going outside a physical location. That is: without using 'random' NTP server on the internet, GPS or whatever.
Most atomic clocks will have 20+ year lifetimes. OCXOs age out a good bit faster, but they're rather cheap (<$200 for ones good enough to provide holdover for a GPS module). TCXOs don't age as quickly (they're not literally in an oven), I'm not sure how long they can be expected to last.