They're only using versioning to indicate breaking changes though. There will never be minor or patch versions in this semver, only ever major (breaking) changes. They're saying "if the version is different in any way, your code might not work because there are breaking changes".

How much the major version changed (v2 -> v3 vs v3 -> v9) doesn't actually tell you how many changes there were. In that way it's almost identical to using major-version-only semver, vs dates.