Yup Oda is a hack.
It's been a clusterfuck of Oda's poor writing habits:
He's fucking lazy and very negligent with his writing hence little to no pay off from established plot points. As opposed to proper build up through events, this mofo takes the lazy way out and uses "statements" instead or just writes in a half-baked conculsion which is even worse and all of these bad habits step from another bad habit of his which is that he's a bloody hype merchant. A bloody snake oil salesman that will write whatever to get your attention and then just fucking abandon it when he's had his fill with hyping it and wants to hype the next best ting
Supernova, Linlin, Kaido, I could go on and on.
Right now his shiny new toy is Loki

Been telling the Loki fanboys even though I'm one myself to temper their expectations but they don't listen but well only time will tell with that one.
Gotta say though with the Holy Knights apart from Oda's hype merchancy with regards to trying to garner the reader's attention, there's quite literally not even an anticlamatic pay off.
With the Supernova, to those that didn't drink the cool aid like myself it was clear that they were just fluff/props to garner attention that weren't going to amount to anything significant (Law's popularity prolly gave them more of a lifeline than Oda intiially intended).
With Kaido, it was to hype up the Yonko saga and Luffy's rise to Yonko.
With the Holy Knights however, what is their purpose even.
With the exception of the deluded amongst us nobody rates those bums and they can't even be killed or defeated without CoC so they can't be opponents for the adult, weak trio or even the revos so what the fck is their purpose? Only ting I can think of atm is that Oda is using them to advitize Imu's abilities to set it up for when he has Teach steal it and have his boys make better use of it. Other than that they are pretty uselsess tbh.