The historical context in 1993 is similar to that in 1917, when Quebec voted almost unanimously for Wilfrid Laurier. In both cases, the outcome reflected people's outrage over an extraordinary political situation.
They are narrow interests in the sense that voters were delivering a scathing condemnation of a situation that obviously required a near-unanimous response, one that would ensure a Quebec-centric voice in Parliament.
With proportional representation, I guarantee you there would be a regional party in every single region of the country. In Ontario, I guarantee you there would be sub-regional parties, including a Toronto-centric party. A Vancouver-centric party would emerge.