Hacking COREBlog for member only comments is rather involved too.

Here's what I did:

Changed Entry.py to check for authenticated users.
Here's the diff

Changed permissions in ZMI to let members only comment

Muddle with CookieCrumbler and login/logout/signup form

After going through this effort, I wondered why COREBlog does not have this OOTB (there's the word again ;))

Maybe it's me. In a perfect world, we probably do not need authentication to post comments. But in my world, users will abuse the system if there's no authentication.

The patch for both Members only Post and Comment is lightly tested. No guarantee that it'll work with the next version of COREBlog.

YMMV