It was simpler to just move from "major.minor and we bump the major infrequently and semi-arbitrarily when the minor is big enough to feel unwieldy" to "bump major for first release of the year" rather than completely change the version number format.

Merely for your consideration, I believe it'd be possible to match both goals by setting next year's version to 2023.0.0

I also didn't know about the leading number being a yearly increment and would have thought 7.0.0 was a substantial change over 6.0.0; setting the number to 2023.0.0 makes that distinction a lot more obvious