Having permanent saturation is not vanilla, there is no way in vanilla minecraft where you can have permanent saturation, having permanent saturation effectively gives you regeneration that's 4x better than the real minecraft regeneration effect.
In vanilla minecraft you're also not able to have permanent strength 2, regeneration, water breathing, night vision etc etc etc. But Manacube gave us these abbilities.
But in vanilla minecraft you are still able to eat as much as you want and you'd get fully healed when you're full. So technically you are able to get healed when you eat in vanilla minecraft, what this saturation effect does is so you don't need to eat to get healed.
Also I think you are also forgetting that WITHOUT this saturation effect/getting healed when you ate is not working AT ALL... So even if you're manually eating, you're not getting healed. That's the core vanilla feature I am talking about that they oh so "fixed".
This is supposed to be 1.21 survival but with this it feels like we're playing 1.8 but with more blocks..
Like I said, if people don't want this returned to PVP then have this abbility be disabled in PVP areas (warp pvp and burninglands).
To have this disabled everywhere like in the wild and in isles is just ridiculous and doesn't make sense.