I don't think it is just the One Click Solution they want (though I don't deny that is probably very attractive). I'm pretty sure we would see more vanity URLs and one-off sites if payment processors weren't so strict when it comes to selling adult content/services. Spinning up a CMS website of your own, even with commerce/membership functionality, isn't difficult. But the payment processors are the unspoken guardians of internet commerce, and without VC level backing good luck getting them to touch something like adult content.

I think this is a missing piece of OFs popularity and usefulness to creators. Not only is it a centralized and (by now) well known site for this kind of content. OF deals with the payment processors, the charge backs, and the disputes. It is relatively seamless for the content creators in that regard.