It seems like some people don't understand the use case for week numbers, at least for businesses. They allow the ability for time series comparisons for a work week. Using the calendar date is hopeless because the 21st day of a month could fall on any day of the week.

I want to compare the Monday of the first work week of the year to the Monday of the first work week of last year. That's most helpful when trying to understand sales trends, etc.