Thats not how it works. One drive creates a one drive folder that sits in your directory. Your directory folder still has the documents/videos folders etc. Inside the newly created one drive folder is a documents/videos folders etc. Onedrive changes the system path to use these folders instead. If onedrive is offline the files can still be saved to the one drive folder. If a programming uses a hardcoded path for some reason then that path still exists because \user\documents still exists and \user\onedrive\documents exists.

Its actually quite simple and works well in my opinion.