I agree but what seems to be missing sometimes is a sentence as to what they expect us to replace the vocal part with (if at all). I would find it much more helpful if they would say 'use a very simple melodic line on top of your instrumental' OR 'no specific main melody is required' (i.e. groove and chord changes are sufficient). If you look at Adele 'Hello' for example (which has been used as a reference in a number of instrumental listings) you will see that there is nothing but a piano with 3-4 chords statically moving underneath the vocals. It is the vocals that make the song and with little instructions it is difficult to guess what the music supervisor has in mind when it comes to an instrumental version. At the end of the day it is better for all of us if there is as little waste of time involved for both composers and screeners. And, last but not least, and slightly off topic

Just my five cents.
Cheers,
Matt