The Import Folders function works well for what it's designed for. And you can't do that on OneNote without third-party tools.
That said, a one-way synchronization (i.e., folder to notebook) in Evernote has benefits beyond backup. I import folders on multiple PCs so I can access them centrally no matter what device I am using. Some of these source PCs do not allow remote access. I could set up cloud drives, but they are simply to slow and clunky to use when working with large multimedia files, for example, or even a simple Word document.
Tried using OneDrive and Word 365. Got messy and experienced sync and file-locking errors. Ditto Google Drive, which gets confused easily when lots of files are being updated, and then either syncs the wrong version or even deletes files and refuses to sync them. Box is just unusable with a terrible UI IMHO. None of these services are ready for prime time or serious business use in my experience. They're good for simple file sharing and lightweight document creation and that's about it. They don't scale. Maybe I should try Dropbox.
Conversely, being able to simply find, grab, and work locally with the file I need via an Evernote folder notebook is convenient and just works. The only downside is that deleted files remain in Evernote. I suppose the easy solution is to periodically delete the folder notebook and reimport it to optimize space.