Well, let's say you and a couple friends are planning a new extension for Flarum. You want to hash out the details in private, just so you won't have to deal with everyone and their uncle saying "You should do this!" and "No, don't do it that way, that's stupid!" 'Cause it's hard to make decisions when you're being pulled this way and that.
Then, when you've got a plan you're ready to go public with, you might decide to throw open the conversation so everyone in the forum can see the thought process that went into it.
In some cases, the need for privacy may just be a temporary thing.
