Usually, when I go to some sort of web-application provider, I must create a login/account with them and register to user their paid services. But with Solid we expect users to authenticate with thier WebId, meaning users already have an account elsewhere - do we then want them to create yet another account for the specific web-application? Potentially meaning they need to login twice to access the service? It seems to me that there should be an easy-to-use standard Solid way of linking accoun...