Do you find the libraries weird?
No, I find the libraries break the filesystem model entirely. They are folder-like entities which aren't folders if you browse via cmd or Powershell, don't have paths associated, can't be enumerated via the standard API, but 'exist' in some half-defined sense only for Explorer.
How do you script writing a file into a library? How do you script renaming a library? How do you configure a corporate application so it installs into a library? How do you write a script to backup your files out of a library when it doesn't even have nameable path? When you write a file to a library, how do you find where it really wrote to? How do you identify where a file you read out of a library is really coming from?
Now, if they'd added the underlying Library concepts (a folder which is a union of multiple read-only and read-write source folders) into the filesystem, at the appropriate level, then I would have been cautiously supportive. It would probably still be a breaking change, but would break far less and integrate into the system automation level well. But as it is...