A difference between YYZ and less busy winter airports is that YYZ is so busy that there is no leeway in the schedule for legitimate winter slowdowns.

However, I'm sure that more could be done to ameliorate the complete meltdowns that YYZ sees in winter. If fueling crews and other ramp staff need to take warm up breaks periodically perhaps the airline/airport authority should call in extra crews and pay some overtime to keep things running a bit better. It might cost a bit more but it would be a drop in the bucket to pay for some extra staff on the 5-20 days a year that the weather is truly bad. Same goes for extra staff for service desks.

Perhaps if the empty passenger bill of rights didn't give a weather exception then there would be financial incentive to make things better.