The 20 minute hand

I just started playing and Last night I went to the game store to play commander. We were supposed to be playing "casual" decks. The one guy played artifacts for the most part, but about the fifth go round, he starts with this crazy feedback loop of scry, kill a card ,use a card ,bring back a card FOR 20 minutes. It was nonsense. He won because his little loop allowed him to create a series of cards that allow give you hundreds of +1/+1 counters and his single swing took out the rest of the group. so I told him I didn't think that he played a casual deck as was agreed. He disagreed.
So community, what do you think about his tactic? Do you agree with me or him? Let me know.