Guys, Katakuri's PREVIOUS design was King level. He even had a different fruit - the powder powder no mi.
However, Oda retconned his ENTIRE characteristics, including his strength, since he should have been mirrored Luffy as the superior opponent. That's why his fruit was similar to Luffy's, that's why he had something - advanced Haki - which Luffy lacked to improve himself through the fight, since he is the underdog.
Both have CoC and both faced each other with their ideals; Katakuri sacrifying his 'freedom' and true identity in order to protect his family meanwhile Luffy doesn't give a shit about appearances and does whatever he likes. Those two IDEALS CLASHED WITH EACH OTHER - and Luffy's won at the end since Katakuri had a proper character development through the fight.
King simply doesn't have that kind of importance in the story, regardless of what he will or could show later on. People need to realise that soon and should stop putting their expectations too high.
Once again, King ain't Katakuri. He is weaker for a reason.