This is a new phenomenon of Toronto fans being bandwagon NFL by the way. For most of their history, the Buffalo Bills were Toronto's NFL team. Obviously, the early 90's was huge for that due to the Super Bowl but even in the 80's it was a thing. It probably peaked around the time Flutie left the Argonauts to play for the Bills.

The main reason is that in the era before satellite, digital cable and internet streaming, Toronto used to catch the Buffalo network affiliates so we enjoyed Bills games and it wasn't really possible to bandwagon another team. This also worked the other way with Buffalo based Blue Jays fans. They got the CBC, Global and CTV and would catch Blue Jays games. Our sports stations would have beat reporters for the Bills and they would be a part of the Toronto local news.

Another reason: Pre/911, it was really easy to cross the border. You used to be able to do it with a driver's license or some form of government ID if you were too young to drive. It was not a big thing for fans to just casually drive across the border and enjoy the game without the hassle of dealing with power tripping border security. It's a bit more of a pain in the ass now that you need a passport. The recent attempts by the Bon Jovi ownership group to move the team to Toronto did not help things either. Toronto and Buffalo seem a lot more disconnected nowadays which is a shame. To me, Buffalo is close enough of a city geographically that I consider their teams to be local and I'm an old school sports fan; you cheer for the team in the city you were raised in. When I was growing up, the Buffalo was an extension of the GTA so I cheered for the Bills.

I know a few Bills players - pre-9/11 of course, actually used to across the border and took the trek across the QEW.