The short BEH routes were mainly to feed mainline flights.
XXX-YHZ-Central Canada was usually cheaper than XXX-YHZ.
An extra Maritime city - YUL DH4 flight could easily replace those 1900s.
Yes the result will be less frequency.
I often connected through YHZ on my frequent trips to YYG.
This allowed more time in J. A few extra points didn't hurt either.
Once J cabin showed up on the YYZ-YYG route, no more YHZ for me.