Despite the fact that Western Canada oil producers can ship their crude oil (if not mixed with U.S. products) to foreign countries using U.S. port facilities in the Gulf Coast area, the volume of Canadian crude oil (essentially light crude) amounts to about 25,000 barrels per day, which represents roughly 0.8% of Canada's total crude oil production.
Canada has an almost complete reliance on the U.S. market for its heavy crude oil exports. Increased pipeline capacity in the U.S. allows to get more Canadian heavy crude oil  to the U.S gulf Coast area where the largest number of refineries in the world that can process Canadian dilbit are concentrated.
According to the U.S. Energy Information Administration (IEA), U.S crude oil imports from Canada in 2016 reached a new level with an average of 3.25 million barrels per day. It reached a peak of 3.56 million barrels per day last November. That same month Alberta lost 13.000 jobs. Building new pipelines won't bring those jobs back.