The last big rockband. The hate was influenced by the industry, because they wanted the rock-genre to go away, it had served it purpose and became unuseful.
Same reason there was a major hate for Creed. Christian Rockband, can't have that. Most of the hate started from sitcom-shows and whatever regurgitate the idea of these bands somehow being okay to hate on, if you wanted to be part of the identity-group of rock-fans.
And i say this without being a fan of Nickleback, don't like their music at all except for maybe one or two songs. But they weren't detestable like for example Rihanna, Lady Gaga, Spice Girls, Backstreet Boys or anything of that kind of shit.