Why must my poor semver be hurt so!

It is fully according to their versioning policy:

https://docs.astral.sh/ruff/versioning/

But also compliant with semver:

Major version zero (0.y.z) is for initial development. Anything MAY change at any time. The public API SHOULD NOT be considered stable.

https://semver.org/

(Maybe I misinterpreted your remark, but semver does not get hurt.)