Registry cleaners are still everywhere in Windows utilities, but why? Microsoft itself has said NOT to use them.
Back in the 2000s, registry cleaners were needed as programs like AOL, Games, and other applications would make a bunch of additions to the registry on install. When uninstalling these programs they would never remove all the entries which would lead to problems. Enter… THE REGISTRY CLEANER! You could run these before reinstalling a program and have it be successful where it would otherwise fail. Contrary to popular belief these cleaners NEVER made your system run faster.
A good example: Final Fantasy XI Online configures the game and has installation directory entries in the Windows Registry even TODAY! Most applications from 20 years ago have been sunset or upgraded to NOT make registry entries.
MARKETING. Cleaners always looked impressive cleaning up thousands of “bad” entries. However, the risk of something going wrong or your system becoming unstable FAR outweighs any cleanup these tools do. The best case is they might clean an old context menu entry, but at it’s worst case it will make your system unstable. DO NOT USE THEM!
If you must use them, CCleaner free has the most proven track record for not messing systems up, but any other tool I’ve seen causes more harm than good and I do NOT recommend using CCleaner.