A lot of the card animations (drawing, summoning, sending to GY, etc) are very quick, and it makes the game feel very choppy when quick animations like these are followed by waiting on a player to confirm actions. An animation speed slider would probably fix this issue, allowing us to slow down card movements so it looks more fluid and also easier to follow.
The animations are async which means the gameplay does not pause or delay when things happen. It’s done like this intentionally so that players can do their combos without any interruption. The movement of the card from field to GY and from deck to hand are just visual. This is why when a card is destroyed, you see an explosion on the field after the card has already left the field. The animations are not synced, but async.
Slowing them down would affect gameplay and then players would complain it’s not as fast. There is always a trade-off and we prefer speed as opposed to sync.