Deleting an Azure Blueprint

Quoting an excerpt from MS Learn page of Azure Blueprint:

"The core blueprint can also be deleted. Deleting the core blueprint also deletes any blueprint versions of that blueprint, including both Draft and Published blueprints. As with deleting a version of a blueprint, deleting the core blueprint doesn't remove the existing assignments of any of the blueprint versions."

The last line in the above quoted text "deleting the core blueprint doesn't remove the existing assignments of any of the blueprint versions" doesn't make sense to me.

How is this possible?  Because if we have to delete the core blueprint, we'll have to unassign it, and deleting the core Blueprint will also delete all the versions, which would automatically mean exiting assignments will have to be removed.