Look at the drama Bruins and Caps series caused on here and it was the first round. Any match with the Leafs will always be on here. The homers will hype everyone to shit and the haters will look for any reason to proclaim to the HF heavens they were right and XYZ really does suck or is over rated.
And then everyone else gets caught up in it, and usually Now imagine the other team had some other storyline to it (like Boston and the 2013 collapse). For example Matthews vs Eichel, or Leafs vs Jets, or Matthews vs McDavid.
Basically pick any team that has a rabid following either for the team itself or for a particular player and watch the shit show.