Some time back in the nineties, Microsoft introduced the Windows Registry. Applications could store settings in different hives. There were hives for application-wide and us
I think that one of the main reasons for this was application updates. When you install an update (i.e. using ClickOnce), the new settings actually go into a new folder. When you uninstall it, the new folder is deleted and the old settings are still around. If the registry were used instead, there would be no way to do this "versioning."
Other reasons might include: