I don't think it will ever be feasible to be charged directly, transaction fees are just way too high (and it's only marginally better on the crypto side). A postpaid system would work I suppose, ie you pay your total at the end of the month. But postpaid usually involves a credit check (in north america at least), so prepaid is really the only universal option.
A bigger problem with paying directly is taxes. Sales taxes and VAT for online sales are often required to be collected by the seller for the buyer’s jurisdiction. If you sell your online content directly to consumers you potentially have to deal with taxes in hundreds of different jurisdictions.
Going through third parties can make it so they are the ones that handle the tax nightmare.
Also "Which sites are using Axate?", I don't recognize any of the sites on that list.