That's a wonderful rant, BazBear. But he still hasn't covered the full madness that is UTC, without even time zones, daylight saving time and international date times. Because UTC can have 61-second (or theoretically 59-second) minutes, it is fundamentally impossible to represent UTC as a single integer count of seconds. You just can't do it. You have to keep it as years, months, days, hours, minutes and seconds, the latter of which can reach 60.
And then you have UTC in the 1960s, before the present leap second system was adopted (in 1972, I think). To keep it in synch with earth rotation time the length of the UTC second was continuously varied relative to the atomic second!
I got into this because I was interested in simulating historical space trajectories, such as those from the Apollo program...I don't know that I ever got past the time conversions.