But that was back before there was only one .CA, and that loophole of "own the .CA and register provincials" likely wasn't around for very long. Today, no one can register provincials and if provincials still exist, no one can register the .CA unless they own and trade in the very last provincial. It's an either-or scenario.
So selling provincial sub-domains, when you also sell the primary .CA to someone else, is an illogical relic from a bygone slice in time.