If I recall correctly, York U is a major destination for a lot of BT riders. From a transit usage perspective it makes sense to have a “1 fare, 1 line” to a heavily-used destination. If we had proper fare integration maybe this “1 line” part would’nt be necessary.
I remember listening to a podcast (The Next Stop?) where it was pointed out that BT tries hard to make transit easier for Brampton’s residents, as opposed to what’s just most efficient for operations.
It _does_ have the highest transit usage growth over the past decade of all the suburban transit operations, so some of their principles must be on point.