"young Université de Montreal professor named Stéphane Dion. ... Laval University, had famously advocated using the threat of separation as a “knife to the throat" to wrest more and more powers for Quebec, "
He was not alone in using separation as a threat to get more power for Quebec.
Quebec was realtively satisfied until the Dominon Conference of 1946. Until then, Canada was a true confederation under the BNA Act of 1867. Constitutional powers between Canada and the Provinces were separate, well defined and respected.
After WW2, the Federal Government's huge increase in spending powers (as a result of having to fund the war effort) meant it could 'buy' into taking over some of the Provinces' constitutional jurisdictions. Poor provinces accepted cash in exchange for relinquishing some of their jurisdictions to the Federal Government. Quebec and Ontario objected to this. That included health care. That's why we have a Federal Ministry of Health, although Health is supposed to be an exclusive Provincial power under the constitution. Then there is the issue of language and culture, which was an exclusinve Provincial jurisdiction until Trudeau decided to make it a national policy.
Canada ceased to be a Confederation in 1946. If became a Federation.
In this context, Quebec governments has since sought to reclaim exclusive jurisdiction it had prior to 1946. And it didn't matter which government. (The difference with Levesque was he was going further than any other politicians). Many saw this change as a betrayal to the agreements made in 1867 that resulted in Quebec accepting to join this new Confederation. Quebec had other options, such as joining the US union, or remaining an autonomous British protectorate. Many historians and politicians see 1946 as a betrayal of the promises made to Quebec in 1867 that got it to join the new Confederation. That included exclusive control over language, culture, health and natural resources. In 1867, swift accommodations were made to Quebec because of the urgency of creating a country: after the US civil war, many US politicians were furious at Britain backing the Confederacy during the US Civil War, and sought to get back at them by invading Canada wih the then huge Continental Army. Plus, there was an opportunity to complete the Manifest Destiny and make all of North America part of the US. Britain had pretty well indicated back in the 1830's that it was not prepared anymore to spend the huge sums of money necessary to defend Canada against the Americans. Those who put Canada together thought that it was better that the British colonies be unified into a country rather than being separate in the face of US aggression.
In a confederation, the parts that make this union are sovereign in their exclusive areas of jurisdiction. That's why each Province has a head of state, the Lieutenant-General, representing the Provincial Crown.