[2020] Why do we need priority to concede?

It's really annoying, and a waste of both the winner's and loser's time.

I'm in a losing match, Azorius control vs. Drakes. In a desperate gamble I try to cast an [[Ixalan's binding]] on either the [[murmuring mystic]] or the 8/4 drake... doesn't matter, my cast is [[thought collapsed]]. Fine. No problem, it happens, concede.

But do I concede? no. After I hit concede I need to watch the card animations, watch the top of my deck milled from the counter, watch another illusion bird spawn, and then pass priority to my opponent and let them draw. Only then am I allowed to leave the game.

I'ts been 24 years since I played paper magic, but I'm pretty sure if someone scooped they didn't need to wait for game priority. I'm sure my opponent wouldn't have minded not needed to watch all of that too.

end of the rant... It's not even the loss that's tilting--its the way I need to wait pointlessly until I can move on to the next game.

Edit: and yes, it occurs to me I might have been able to make a stop at the end of the turn to get priority a little earlier for the concede to go through, but that still doesn't answer the question: why?