Sure but not doing it on ENOENT suggests they’re just being completely lazy. Not to mention that they do have the tools (eg inotify watches) to proactively remove stale entries based on HD changes. Of course I’d be careful about the proactive one as it’s really easy to screw things up more (eg 100 bash instances all watching the same PATH directories might get expensive or forgetting to only do this for interactive mode connected to a TTY)