There are more benefits with the browser sandbox than just plain old file access. Web apps can’t just read the clipboard or enter scripts/commands or take screenshots or activate webcam and microphone

For all practical purposes, file system sandbox features might actually be the first to become meaningless again when more and more data is stored in offline browser caches

And application delivery in enterprise environments is also much more lightweight compared to VDI solutions like Citrix so there’s another benefit in terms of sandbox and isolation