Can you please clarify what would be the purpose of having a private vendor topic in this site?
What would be some example of topics that could be discussed in such vendor private topic?
The main thing is that the general discussion topic will be returned in google search results. The private topics will not. In the event you want to ask business questions or divulge some aspect about your business that you only want to discuss with other vendors there is a place for that. Same with the support topic. It also gives Atlassian another channel to communicate to vendors on issues we might not be ready to publicly announce.