Tbf having thought of it I can see where Kid and Law fans were coming from.
They had to watch Law cry, crippled, on the ground while Luffy stepped in and achieved his lifelong dream of beating Doflamingo. He’s not even going to be the one to achieve his new dream, Robin will do that.
And we know Kid is getting no nearer to achieving his dream of being the Pirate King than Don Krieg did in East Blue.
So it’s understandable that they think that Kid and Law might get to steal the goals of Luffy and Zoro. Alas, that is the difference between the two pairs, the main characters get to achieve their goals. The side characters only get to cheer in the background and get tossed characters like Big Mom that Oda simply wants to get rid of as quickly as possible.