We see many users in the forums who need to reconnect their folders in LR, because they moved folder structures from outside of LR or a drive letter changed on the drive where the images are stored. Many of those users only realize the need to do the reconnect after the fact that the folders are missing.
If they did not have a hierarchical view in their folder panel active and parent folders added before the folders "got lost", they have to reconnect each and every single folder, which can be very cumbersome.
Having an option to "Add Parent Folder" also for missing folders would help a lot in those cases. As far as I can see the information needed should be available in the catalog even if the folders are missing already.