dzham Indeed, this would even make the implementation simpler, given you can do it synchronously rather than watching transactions for website address.
I also love how this kind of auth combined with low fees from stellar would make it possible to have new kinds of pricing plans, like for example paying per session rather than subscribing per month. For example, someone who want to read articles from paywalled press could pay 50c for a 2 hours access, the payment would be included in the authentication, and fees would be small enough to make it viable. The press company would get money from all those users who want to read one or two or their articles but are not willing to pay full monthly access for that.