Valve won't let Steam have bitcoin purchases because their policy for returning money back will make them incur losses dealing with fees and payment processing companies. The Arkham Knight debacle called for so many refunds that I am not sure Steam could handle bitcoins refunds like ever lol.
well if they didnt use bitcoin for pre-orders and game deliveries (where issues could occur) but instead for ingame 'fancies' like gold, bullets, vehicles.. where once they are bought the customer has to keep. there would be no issue
This could work but I think the easiest solution to this is just allowing people to buy Steam gift cards with bitcoins to do whatever they want so in case of unsatisfied customers Steam will just return the amount to their Steam wallet no issues there.