This is nonsense. Safari adds major features in point releases: just look through some of https://developer.apple.com/documentation/safari-release-not... and see. Some of the biggest features get held for the next “major” number bump, certainly, but most point releases include at least as much as most major number bumps in Firefox or Chromium.

In my experience, people haven’t tended to use just “last two versions” with Browserlist: IE has normally been special-cased historically, and Safari has regularly been special-cased in some way, and Safari has actually been the salvation of the “last two versions” strategy because it dragged the baseline down to a more acceptable place, where “last two versions” of only Firefox and Chromium would regularly be disastrous. It has long been a really poorly-thought-out mechanism.

The other point you’re missing is user adoption. “At least one year” for Safari is one thing, but “five weeks” for everyone else is pretty crazy when you look at actual update statistics.