I can agree as well, but some apps treat the second display differently. Lumps Fusion puts the preview video on the external monitor. MindMap puts a full view of the mindmap on the external with a smaller view on the iPad display. There are likely others. I use my iPad Pro as my primary computing device. Yes, the workflow can be frustrating, but I have also taken advantage of ShortCuts to help with some of it, if the app supports Shortcuts.
Work provides me with a Macbook Pro. The only thing I can do on it that I can’t do on my iPad Pro is a local terminal. But, workflows differ!
Good luck and thanks for the article.