I originally was going to write a question about how I could have a public site but not show user profiles to non-logged-in users. I was starting to get concerned about the issue.
Then, I looked a bit more, and found the “hide user profiles from public” option under settings/users. Problem solved, just like that.
There have been a number of times this kind of thing has happened: Something that I thought would be an issue or at least something that would take a lot of effort, being solved quickly and easily by a setting the Discourse team has thought of.
Awesome awesome work.