This brings up a further issue that needs clarification. Do sites that operate SMTs require their users to have a steem user id (that could be used to login to steemit, for example) - or not. I imagine that such a username/id would be required, but I haven't seen anything about mechanisms for perhaps autocreating the names for people who are members of your site, but not of steem/steemit.

Additionally, there is the question of whether posts to your site will be visible in Steemit or not - which is something else I haven't seen mentioned anywhere that I have looked yet.