A few years ago I buit a personal file storage server [0] that was interoperable with OwnCloud and sync based on WebDAV. Over a decade ago I worked on a site builder that used WebDAV under the hood. What I found was that WebDAV is mostly fine if you control both client and server, but then there's less point in using WebDAV. But the allure has always been there: let your users mount your app as a filesystem and update your app's content locally using their own tools, with syncing for free.
In practice, the syncing was never reliable enough for most users, and different clients implement the standard differently. My hope was that it would eventually converge on something interoperable like CSS did, but I don't think there's enough usage for that to happen. And things are moving away from filesystem paradigms anyway (iOS, etc) so WebDAV is slowly becoming even less relevant.
I used it for an Adobe Acrobat project years ago. Acrobat Pro let you store comments via WebDAV in a way that you could collaborate on a single PDF and see all comments from all users.
But, you needed to set everything else up on your own. I built a system that filled in the gaps that was used to proof corporate documentation and clinical drug trial materials.
In practice, the syncing was never reliable enough for most users, and different clients implement the standard differently. My hope was that it would eventually converge on something interoperable like CSS did, but I don't think there's enough usage for that to happen. And things are moving away from filesystem paradigms anyway (iOS, etc) so WebDAV is slowly becoming even less relevant.
0. https://github.com/mnutt/davros