> The private citizen has the option to pay cash, bitcoin, trade goods or services, etc.

As far as I understand, this isn't an option. I'm Brazilian, so I can easily pay with PIX (and I have never used a credit card with Steam, since PIX is just so much more convenient). But Steam isn't allowed to sell me that content; if they try, even if they restrict it only to those who pay with PIX, my understanding is that these two global payment processors will stop working with them. And since unfortunately most of the world doesn't have yet something similar to PIX, that would mean losing access to a lot of people.