The master key may also be used to sign other items such as the backup key
Given her master key is compromised (and that is the case when she'd like to rotate) nothing stops the compromised to issue and sign a new backup key.
Better: use pre-rotation of KERI.
a master key (MSK) that serves as the user’s identity in cross-signing and signs their other cross-signing keys
Is a point of failure / weakest link in this chain - compomise of one key is enough to compromise Alice's identity.
Also, requires it to be replicated across her divecise, if she wishes to add new device from any device.