Not sure if you were telling us about Vancouver also which is great.
My article was about the cruise ships that 'Stop in Victoria', not Vancouver.
Majority stop because of the USA law called the Jones Act.
See Victoria Schedule as theses ships normally do not go to Vancouver unless an extended voyage up or down on the Pacific Coast.
Greater Victoria Harbour Authority
A law called the Jones act which states that all ships which are registered in a foreign port(which means all cruise ships in the USA), must go to a foreign port(Canada) by law. Even when you cruise to Hawaii, the cruise ships go down to Ensenada or somewhere in Mexico.