As the Wikipedia page linked to by the article points out, "over long periods of time a calendar based on the sidereal year will drift out of sync with the seas

As the Wikipedia page linked to by the article points out, "over long periods of time a calendar based on the sidereal year will drift out of sync with the seasons at the rate of about one day every 72 years." Even more annoyingly for fans of modernist rationalist calendars, the length of the tropical year varies depending on how you measure it (from one vernal equinox to the next? or from one autumnal equinox to the next?). More long term, the Earth's rotation is slowing even without the aid of government support. (Yes, I realise the article is a satire, but the challenges are greater than those it refers to.)