When a LLD rule creates some item/trigger the entity works independently of the LLD.
If the item is no longer found by the LLD it is marked for removal according to "Keep lost resources" settings, but keeps working normally.
In certain scenarios it would be very useful to allow automatically disabling such items.
Example - LLD discovered mounted FS - /mnt
It has some free space:

zabbix_get -s 127.0.0.1 -k vfs.fs.size[/mnt,pfree]
9.223341

There is also /:

zabbix_get -s 127.0.0.1 -k vfs.fs.size[/,pfree]
28.615649

If /mnt gets unmounted shortly, the item still works, but returns value for FS /

zabbix_get -s 127.0.0.1 -k vfs.fs.size[/mnt,pfree]
28.615649

This can lead to incorrect data in item history and most importantly falsely firing triggers.

An optional rule to disable these items/triggers when LLD doesn't find them any more could help here.