It's the trendy thing to do in webmaster-dom. Gotta be secure, dontcha know. Privacy matters!
In FR's context, all it means is, your ISP won't know where on FR you surfed or what, if anything, you posted, but it will still know that you are an FR user.
We aren’t the “super-secret underground conservative site”?!? :-) I am not experiencing the “HTTPS” error because Safari handles that differently than IE or Edge or FF, but I am still having the “partial page load” issue.
Additional info. on avoiding the “HTTPS errors” on Windows: