New years day is always a holiday that doesn't fall on any other day of the calendar. It's just kind of its own thing. No idea how that would actually work irl but that is usually how this proposal is explained.
Kinda sounds easier to implement tbh, like, right now leap days are in a specific month, but wouldn't it (in addition to a hypothetical new years day) be easier to handle and remember if they are a very explicit part of the calendar system?
On the one hand, yes. On the other hand, now there is a day that is not part of a week, or a month. And we have a month and a week that don’t immediately follow after the previous one.