Which isn't why we created to Unix Epoch anyway? The number of seconds since an arbitrary event, with no regard of the movement of celestial bodies? And isn't

Which isn't why we created to Unix Epoch anyway? The number of seconds since an arbitrary event, with no regard of the movement of celestial bodies? And isn't Unix Epoch derived from some sort of Atomic clock standard? I can't remember, but it seems all of our systems time should be atomic time, then you can derive UTC or whatever you want from that.