@heluecht The classic use case is someone victim of a massive or coordinated harassment campaign, hundreds or thousands of people leaving provocative replies on public posts. As a reaction, the user switches their account to restricted (or "protected" on Twitter), only allowing their followers to interact even with their public posts.

I don't even know if the current Friendica feature allows this, but having public posts available through the one-way feed isn't necessarily an issue in this context. Besides, we could also restrict access to the feed based on this setting.