This may be a naive take, so if anyone has insight please feel free to share, but across Windows, Mac, and Linux OS's I see many cases of path parsing vulnerabilities resulting in sandbox escapes, code execution, or data access issues. When presenting the user with a file picker or command-line input, is it really needed that the software can handle the full POSIX spec?

I do not see a "typical" user needing to access a path with say a network storage but multiple ../.. and hard and soft symlinks simultaneously. I think "be liberal in what you accept" might need to be revisited for path parsing with some sort of OS-wide single-implementation as an optional feature.