I know why people on NeoGAF act like K. Rool's popularity sprang out of nowhere. He was popular pre-release too, rivaling Ridley in many polls. Even worse is this fabricated notion that Ridley/Geno fans (HAHA THEY ARE SO DELUSIONAL!!!!11) are now "bandwagoning" to K. Rool because... what exactly do Geno and K. Rool have in common that would lead you to make that connection? On the other hand, a case can be made that people started bandwagoning to Dixie because she appeared in Tropical Freeze and K. Rool didn't. This lead to everybody to declare that Dixie was a shoe-in, K. Rool was dead, and he'd be lucky to get a trophy. As it turns out, neither character got in. It sucked to be a Donkey Kong fan. The ballot has rightfully given us a platform to voice our disapproval with the amount of DK representation in Smash.
To quote what a SmashBoards user said, I don't feel like K. Rool's supporters are bandwagoning because of the confirmation bias that plagues so many choices in the Smash community. His support doesn't hinge on a ridiculous fan-made rule, it's mostly made up of people who genuinely love the character and the franchise he hails from. He doesn't have any flashy new game appearances, potentially credible rumors, or developers literally begging for his inclusion. Yet he continues to be a highly requested character worldwide. K. Rool's support is as grassroots as it comes, now matter how hard people try to downplay it.