I think it's useful, expecially if you are playing with people you don't know well, but has a few issues. Two of which are worth mentioning. The first one is the advice before moving to a new scene to stop the action and tell that there could be trigger topics, even if as the DM you know the content of the scene doesn't have any topic that were checked out. This break the pace and immersiviness, think of a movie where every 10 minutes everything stops and the actors ask the public if everything ok. The second, to use the example provided, is the possibility to stop a campaign before it begins. If I propose a post apocalyptic game and I have enough players and somebody comes and tells me "I want to play with you, but you should create a new campaign just for me" my answer isn't a yes, just to put it politely. A good beginning, but could have been way better.