This might look like a big list, but let's not forget the sites on this list are owned by the same big company. So from the dozens of really big porn company's, there are only a handfull that have implemented a payment gateway that allows bitcoin or altcoin payments...
Aside from this list other big players in the industry have opened up to BTC/altcoins as well. I think the bigger problem here is people using the cryptos - it's still a bit of a process to get bitcoin before you can spend it and even then it's just easier to use a credit card direct on the site. I see you can use Paypal on a number of adult sites now too.
I think its more about getting people to use cryptos, other players in the industry will open up to it quicker when they see it is being used more.