The job of the registry is to be a reliable structured storage with access control and other features. It is not responsible for the things that go into itself.
If you put together a structure like that and leave the sordid details up to the implementer and you supply a mostly confusing example as the set shipped with the OS, and subsequently mess it up even further with your own application installs you own the mess.
An upvote isn't always enough, so I just want to say I support your holistic view of engineering and find the "not a bug, not my problem" approach detrimental to the broader success and acceptance of technology in society.
I'm unable to extract anything specific from your comments. Are you still talking about the registry or about something else? Its cathartic to vent, but the registry is not the source of your frustration.
Okay.. call me small-picture-minded but I much rather prefer - "I press a button M and Feature X doesn't work when I choose option Y" - over "Feature X is terrible at its job"
The problem is not that they don't work as intended, the problem is what is intended. You can't just throw application developers an API like a system wide key value store and expect the whole worlds ecosystem of applications to organize itself around it. Android and iOS solve this much better by sandboxing application settings within the app. Uninstalling the app is guaranteed to remove any traces of it (unless you give access to "all files and photos"), whereas on windows there is always some remains.
Its just a database. Using the registry is not a requirement for any app. They can store their configuration in a text file, they can store it in the cloud, they can do whatever they want, they can even create a C:\etc and store it there :)
Sure, there exist badly behaving apps that don't clean up after themselves when they're uninstalled. Windows gives apps the freedom to choose their own method of installation, but some vendors abuse those freedoms. I don't quite know what the OS is supposed to do about that. Windows already does an insane amount of work trying to keep buggy apps running, something that macOS or iOS or Android or Linux don't. The fundamental goal of any consumer OS should be making sure that the software a user purchased continues to work.
>Android and iOS solve this much better by sandboxing application settings within the app.
So, multiple users on a device = separate settings = multiple app installs? That might work OK for consumer devices, but won't really fly in the IT world.