Accepting bitcoin payments with 0 confirmations? It shows a complete lack of understanding of Bitcoin and cryptocurrency in general, especially in 2017 when PoW was the main driver and PoS chains weren't really mainstream.
It’s not a big deal in case of Steam – they can just pull the games from your library if the payment doesn’t go through. A bit trickier with in-game purchases (but in that case they could wait for the confirmations).