TTL

The kernel isn't storing anything to implement this, everything is happening before the return of the syscall. A TTL would require adding extra data to the page cache. That would have lots of overhead, and require that the TTL be checked all over the place.

It would likely be bad for performance. Plus you as someone calling IO have no idea what else might be using the file, this is a hint about how the program doing the IO expects to use the IO, not system wide.