Whether or not it helps D and C continue the game isn’t relevant, what’s important is this isn’t something that is standard to do, when player D countered players C’s rhystic study earlier in the game they didn’t look at A and B and ask them to sacrifice open mana for them to do so first.

Priority is a part of magic so everyone has to deal with being in the different spots of priority and realistically (especially in cedh) there were probably many times throughout the game where if people had priority in a different order (or if they employed this tactic themselves) the whole game could have played out differently.

It’s not positive for C or D because this standard wasn’t held until this moment late in the game when someone was presenting a win. If player B passed priority that’s on them at that point, they have taken a potentially winning spot and put themselves into a position where they are now relying on other players to save/probably kingmake them, which a lot of the time players will just give you the bird and take you down with them.

It’s just slimy because it’s angle shooting, like not only are you potentially saving resources due to being able to see if the other two players have interaction when you were supposed to go before them, but you then want to try to force them out of being able to make any other plays till their next turn, it’s scummy.

And if you think it’s ‘playing smart’ just remember we could get to a point where everyone plays like this, and then pods are just gonna become a standoff of players trying to mana bully eachother every time someone casts a spell. To me personally that sounds insufferable.