You say that it is sorted in the order of most significants, so for a date it is more significant if it happend 1024, 2024 or 9024?
Most significant to least significant digit has a strict mathematical definition, that you don't seem to be following, and applies to all numbers, not just numerical representations of dates.
And most importantly, the YYYY-MM-DD format is extensible into hh:mm:as too, within the same schema, out to the level of precision appropriate for the context. I can identify a specific year when the month doesn't matter, a specific month when the day doesn't matter, a specific day when the hour doesn't matter, and on down to minutes, seconds, and decimal portions of seconds to whatever precision I'd like.