Well you did said about volatile so that's one of the reason why some of the big companies or even the smaller ones are not gonna accepting bitcoin as their payment because of how volatile the market is and it could either make the company profit of their bitcoins or things will go in the opposite way. The other reason is transaction fee but it's not a big deal.

Steam was accepting Bitcoin for quite some time but unfortunately they removed it: https://hexus.net/business/news/internet/112973-valve-removes-bitcoin-payment-option-steam/