....Diddy doesn't equate to free wins. Of course, he is currently the character with the best tools, but unless your opponent literally leaves their controller on the floor, the win isn't free; tools need users to operate them, after all!The only reason Robin is meh ranked is because he takes time and dedication to master and nobody has that time, especially when there are easier characters to scrub as. *cough, Diddy Kong, cough*
Thinking of Diddy as a "press this button to win" leads to lenience; it leads to less practice, less match-up experience, and most importantly, less moving forward of an infinitely complex metagame.