Economic growth isn't the only thing that people care about. If you tell people that "the cost of this policy will be reduced economic growth"–some will view that as a price worth paying. Likely that's true even for you – not for this policy, but for other.
And Quebec and Alberta have very different economies, so I'm not sure how confident we can be that former predicts the likely future trajectory of the latter.
Economic growth isn't the only thing that people care about. If you tell people that "the cost of this policy will be reduced economic growth"–some will view that as a price worth paying. Likely that's true even for you – not for this policy, but for other.
And Quebec and Alberta have very different economies, so I'm not sure how confident we can be that former predicts the likely future trajectory of the latter.