Why a 'local' mountpoint does not get deleted after zfs destroy?

[youzhongyang]

The following piece of code does not rmdir the mountpoint if it is 'local':

https://github.com/openzfs/zfs/blob/master/lib/libzfs/libzfs_mount.c#L874

void
remove_mountpoint(zfs_handle_t *zhp)
{
	char mountpoint[ZFS_MAXPROPLEN];
	zprop_source_t source;

	if (!zfs_is_mountable(zhp, mountpoint, sizeof (mountpoint),
	    &source, 0))
		return;

	if (source == ZPROP_SRC_DEFAULT ||
	    source == ZPROP_SRC_INHERITED) {
		/*
		 * Try to remove the directory, silently ignoring any errors.
		 * The filesystem may have since been removed or moved around,
		 * and this error isn't really useful to the administrator in
		 * any way.
		 */
		(void) rmdir(mountpoint);
	}
}

Any reason why this is the case? The mountpoint is created if it does not exist at the time when the zfs file system is created and mounted.