I think it was only done for fanservice
Oda knew the fans wanted Luffy and to be a yonko so he made him one but he had no intention of changing his way of writing to have the crew living up to their status
It was bad enough when he declared Luffy a 5th Emperor post WCI but Luffy "earned it" by end of Wano imo, after the biggest asspulls and retcons we've ever seen though ofc and Oda truly embraced them being a Yonko crew now by clowning them as he does to Yonko crews, just look at how he treated Jack, Pekoms at WCI, the infamous waterfall incident with Big Mom herself too and her "amnesia" and Smoothie, a YC2 who cant even handle a waterfall nor get past a fucking door too, Queen sabotaging way more of his own forces/alliances, King not having CoC etc.
Newer generations of powerful roles in anime seem to be far weaker though, looking at some of the awful choices of new captains in Bleach after the series ends, most of the new (why are they) Kages in Naruto post EOS etc, I wouldn't be surprised if newer Yonkos were weaker than previous ones...oh wait Luffy and Buggy lol.
The fact Oda didnt even let Big Mom and Kaido have awakenings purposely because there's no way they would lost if they had, he could not write a believable defeat for either of them if they had, but then again, their defeats were barely believable as it is ofc.