@Protoaddct pretty much what @diophan said. there are no rules requiring you to play to win. you have to play at a reasonable pace. if your whole deck is just wraths of gods, balance, winter orb, armageddon, stasis, propaganda etc, that's fine. I've definitely seen games in the past where someone could've won but didn't to get more information or because he thought it's better to win the first game after 30 minutes and likely win the match 1-0. if your opponent doesn't concede, I am not aware of any rules that tell you to win the game as soon as possible. You cannot alter your play style to be slower to waste more time though, that's cheating. Sadly very tough for the judges to spot too.
I've played decks in Standard a long time ago that could barely win game 1 but could completely lock the opponent out from doing anything with the only win condition being gaea's blessing. if they won't want to concede, sure, they will eventually get decked and won't be able to finish game 2, that's their problem. I had more stuff in the board to win games faster in case it was 0-1 or 1-1. but building a deck like that is perfectly fine.