Comment by Calamityjanitor

I think you're describing the exact confusion that developers have. Unix time doesn't include leap seconds, but they are real seconds that happened. Consider a system that counts days since 1970, but ignores leap years so doesn't count Feb 29. Those 29ths were actual days, just recorded strangely in the calendar. A system that ignores them is going to give you an inaccurate number of days since 1970.