The reason churches are deserted is because of the quiet revolution in the second half of the 20th century following the Duplessis government and not the inability to buy consecration wine.
https://en.wikipedia.org/wiki/Quiet_Revolution
https://fr.wikipedia.org/wiki/R%C3%A9volution_tranquille
Quiet Revolution
The Quiet Revolution (French: Révolution tranquille) was a period of intense socio-political and socio-cultural change in the Canadian province of Quebec, characterized by the effective secularization of government, the creation of a welfare state (état-providence), and realignment of politics into federalist and sovereignist factions and the eventual election of a pro-sovereignty provincial government in the 1976 election. The Quiet Revolution typically refers to the efforts made by the Liberal governments of Jean Lesage (elected in 1960) and Robert Bourassa (elected in 1970), though given the profound effect of the changes, most provincial governments since the early 1960s have maintained an orientation based on core concepts developed and implemented in that era.
A primary change was an effort by the provincial government to take more direct control over the fields of health care and education, which had previously been in the hands of the Roman Catholic Church. It created ministries of Health and Education, expanded the public service, and made massive investments in the public education system and provincial infrastructure.
So that is the reason... It had to be something more complicated than the consecration wine definitely hahahah.