The Sedins did not fight back against Marchand because non-retaliation was crucial to the Canucks' entire game plan. They went into the series with a lethal power-play. Vigneault's plan was to let the Bruins draw penalties and then kill them on the PP. The crime in that incident was NOT that Sedin was following the game plan and being a great team player willing to take punishment and humiliation in order to help the team win. It was that the refs declined to call the series in any fashion resembling an actual organized sport, and absolutely not in any fashion consistent with how penalties had been called before that. So a Marchand had free rein to bitch-slap star players all he liked without any fear of being penalized. The Canucks could not win that kind of series.
The list of blood-and-guts Euros goes on and on. Lidstrom. Datsyuk. Zetterberg. Forsberg. Chara. Plekanec. Koivu. Salming. Alfreddson. Pleaknec. The Sedins (one of whom merely racked up an iron man streak of 600+ games - wow, what a pussy). Mats Naslund. Etc. etc. etc. This whole thing is a ridiculous trope. Remember when Ottawa dealt Hossa for Heatly and all the fans were excited that they'd finally "Canadianized" the team? How'd that work out? Last I checked, Hossa is the guy with Cup rings and Heatly has degenrated into a whiny mediocrity. None of this has any effect on the stereotype, of course. When a Canadian player is a lazy slob or a bad team guy, that NEVER says anything about Canadian hockey, right? But when a Euro is, well, that's all the evidence we need.
It's called confirmation bias, and it's mostly a bunch of bunk.