Eh… this is a poor argument imo. We’re talking about hot seat between friends. Competitive integrity shouldn’t be a consideration here.
Look at Heroes of Might and Magic III as an example. I used to play this game probably hundreds of hours with friends growing up, all on the same computer. And similar to Yu-Gi-Oh, when its your friend’s turn, you’re not supposed to see what they’re doing. How many heroes they have, how they’re moving their heroes across the map, what they decided to build, etc.
The only valid reason for not being able to do what OP is asking, is a technical one. You’re not harming competitive rankings or otherwise damaging the integrity of the game for the community. You’re just allowing two friends to play how they want to play. The two players, if they really wanna turn their heads, will just communicate and the game will shift control from side to side based on the rules.
Personally, I’d use a feature like that to test decks. Its currently really annoying and difficult to test interactions in the game. To the point where I’ve actually started using a VM to boot the game up in on a different account so I can play myself.
tldr; I think this is a good feature ask. At the same time, my guess is this would be a very large tech change for a niche use case.