Our agency does not use XD collaboratively for a number of reasons. Instead, we have multiple people with individual Creative Cloud accounts opening and working in XD files that are saved on our Google drive.
With other Adobe CC programs, if one person is currently editing a document and another person opens the document, the person just opening the document (sometimes) receives an alert that someone else is currently editing said document. This feature would be a massive help to include in all Adobe CC programs, but specifically XD.
As stated in the original post, we do not use the collaborative feature of Adobe XD due to the required storage on the Adobe Creative Cloud and due to all the issues described by many posts in the XD Support Forum.
Similarly to what is described in this post, InDesign USED to alert people when more than one person was in the document. I imagine that because collaboration is the goal of the new versions, neither InDesign or XD alert you when someone else is already in the file when you are not using the collaborative/cloud versions. Again, we do not wish to use the collaborative/cloud versions of any program due to issues with saving, security, etc.
It seems that prior to the introduction of these collaborative versions of the products, the alerts were being made in at least some of the programs. My request is to consider reintroducing these types of alerts to all programs, regardless of whether the file is saved locally or on the Adobe CC.