I’m not sure why it’s called a Playlist actually. It’s function really is as a media bin.
For example, the playlist doesn’t sequentially play the source files one after the other, so what’s it doing being called a ‘play’ ‘list’ ??
But you can export from the playlist where the source clips will be exported in the sequence you have set, so it makes some sense there as a list. But adding a clip to the timeline means you now have a project, changing the playlist sequence then becomes redundant.