Again, I think people have overestimated the importance of the Gifters to Kaido's base of power. That might be partially on Oda for building them up the wrong way, but there's a few metrics we can use to weigh their actual in-universe importance.
Firstly, Smiles seem to be a relatively recent development. Vegapunk's prototype is more than four years old, but the mass-produced ones only became viable enough for Doflamingo to divest his slave investments in favour of them two years ago. Kaido has been a dominant force on the seas for far longer than Smiles even existed in any usable capacity. They were never the foundation of his power, just the novel new addition to it.
(and isn't it a classic trope for the villain's fun new weapon to be turned on them at the climax of the battle?)
Law says as the crew leaves Punk Hazard that there are around 500 artificial zoan users on Kaido's crew. We now know Kaido's forces number around 30,000. All up, the Gifters represent only 1.7% of Kaido's total forces. Even accounting for them only being turned after the force was reduced by 5,000, and assuming all Gifters are still in fighting condition to be turned, that only brings it up to 2% of the remaining crew.
A Gifter is surely worth more in a fight than the average fruitless pirate, but 50 times more? If it was all the Gifters against the rest of the crew, I wouldn't bet on the Gifters. Ever since we've arrived at Wano, we've seen up close that Gifters make great enforcers over the commonfolk, but a Smile alone isn't enough to come close to challenging someone in Luffy's ballpark. All of Kaido's executives use traditional Devil Fruits, and that's probably not a conincidence.
Tama hasn't singlehandedly turned the tide of the battle here, just edged it literally a couple of percent more in the heroes' favour in a way that was both foreseen and inevitable.
But Oda did make his own bed in a few ways. 500 seems like an overwhelming number when it's presented at Punk Hazard. The crew have taken down larger armies by that stage, like the force at Ennies Lobby or the hoard of underlings brought in by the New Fishman Pirates, but our best reference for a crew of Zoan types was CP9, and 500 of them is a pretty daunting opposition. We also had no way of knowing yet how small a portion of the overall crew those 500 were. Smile production was also a huge plot point in both Punk Hazard and Dressrosa, putting more narrative weight on them before Wano could provide perspective. I don't blame Oda for going that way; Devil Fruits and the idea of mass-producing them is a fascinating part of the series worldbuilding that everyone wants to learn more about. I don't think I can rightly blame people for having higher expectations for the Gifters.
But for me, looking back at how they actually stack up in-universe and in terms of numbers, I just can't see the whole Tama thing as the big deal its become to some people.