The title sums it up. Such a feature could be useful for tournaments/"important" games, for more social interactions with friends, etc. This wouldn't require to store replays either, or anything like that. Similiar to chess,tcg,pokemon or other turn-based game websites, one could have a history of replay relevant plays/in-game steps(aswell as the map setup, and whatever else may be relevant), which can be copy pasted. A replay function could re-create the game from this information. A spectator mode already exists, so i guess this shouldn't be much of a leap. You'd simply be spectating a scripted game. I wrote "partial" because certain things may be unnecessary to track, such as the cards in the hand of the players you aren't spectating, outside of their amount. Given i don't know how the website runs, i could only guess what may be easier or harder to track/implement, so i won't speculate on that.