All of what you said doesn’t change the fact that building up a character for the purpose of using that character to make another character look cool is cheap and lazy writing lol.
Why would Luffy and Sanji fans give up? Not only have neither of them ever taken an L this hard, but they are also the MCs. Of course they will bounce back. Kidd already got this treatment with Kaido when he got whooped thrown into prison and had his RHM fed a SMILE fruit
Constantly dunking on a character is just repetitive nonsense and it’s not building anything. No one thought he would win, but losing like THIS is ridiculous
Just because your headcannon hasn't come true or you didnt like something, it doesn't become bad writing. Not taking Oda's side in all what he does but Kidd getting rekt isn't bad writing at all. He has no role to play, he isn't Shanks, BB or Luffy, he doesn't have a D. in his name like Law, he simply had to be written off.
Nobody here has any kind of good writing awards. Many are liking it, those who don't don't matter at all. Just because a random man says its bad, it doesnt become bad. Prove that its bad writing, if I am not satisfied with your explanation, you are wrong.