Even if are "down to several nano-seconds", a slight clock drift can be the different between corrupt data or not, and when running at scale, it's only a matter of time before you start running into race conditions.
For a small web app, fine, but if you're running enterprise level software processing billions of DB transactions per day, clocks just don't cut it.
For a small web app, fine, but if you're running enterprise level software processing billions of DB transactions per day, clocks just don't cut it.