The “Discourse as user accounts manager” use case fits my needs as well. The only other component of our website that handles (large amounts of-) users is DokuWiki, and we certainly don’t want our simple (and not always up to date) wiki system to be the keeper of user info.
Discourse, with its trust levels, likes, badges, rich profiles and extensive API makes for an ideal userhub. I get that most people right now need to do it the other way around because they’ve built the entirety of their site out from the WordPress core. But WordPress really isn’t built for non-editorial users out of the box, so for new sites I don’t think it makes a lot of sense to have WordPress as the central userhub.
If someone is using Discourse as the SSO authority for other applications, please share.