>>96425944
It was intended for two decks (DM and Adventure) that would only ever get into it by DNA Digivolving two ACEs.
So it "needed" total effect immunity to prevent Overflow -8 from ever happening, and those decks had to run full lines of Digimon to be effective, so didn't have room for more than one type of Omnimon. They even limited the "DNA and attack" effect on those Aces to Alter-S specifically.

But BT22 was right around the corner and with it
>memory setter that plays a rookie every turn
>new Gabumon and Agumon, each with consistency On Play effects and End of Your Turn DNA
>a black egg that they could evolve from, allowing players to run the original Alter-S searcher rookies from EX4
>another warp MetalGarurumon and WarGreymon, each with the same inherited effects as the BT17 ones
>a third DNA Omnimon
Because Warp Omnimon only runs Rookies, Megas and Omnimons, it can run 7+ Omnimon to always have one in had if it keeps then after Alter-S does its thing.
If they don't keep turn, they threaten Omnimon Ace (Blitz and Cres can't do that) and you can't remove either part because Miraculous Mega Knight lets it DNA Digivolve with a card in the HAND to avoid removal.

It used to be that if they used MMK they had an ACE that was a sitting duck for overflow. Now they can use it to go into Alter-S and be completely immune, or worst case, just bottom deck one of your Digimon with Nokia's Omnimon.