Groups can be modified into blogs

It’s just an assumption, not necessarily true. Jami’s group seems to be able to be modified into a blog, where bloggers can post and followers can reply.
Blog articles and comments can be forwarded through the group’s network.

So the blogger is like the administrator of the group, and the followers are like ordinary members of the group.
A group is no longer a regular group, but a group with the same functions as a blog.
Bloggers can choose to ban a follower instead of directly kicking them out.

There would need some changes but it’s a planned feature in the long term yes