Those of us who think that a polluted registry file caused them problems are just imagining things, that can not be. Windows has been devised in such a way that it can deal with all that clutter in the registry. There's nothing wrong with loads of junk in the registry. It is not a bug in the design, it is a feature in the best of Microsoft tradition.
You are correct in that a "polluted" registry DID cause problems in Windows 9x and XP
Since the advent of Windows 7, the way Windows accesses the registry has changed. In prior versions, applications would search the registry for the entries relating to that application.
In Windows 7 and above, applications' registry entries are "hard wired" to that app, hence the app doesn't search for the entries, it goes straight to them.
That's why orphaned entries in Win 7, 8, and 10 registries don't affect anything, and why there's no need to use any sort of "cleaner"