Out of your perfect scnarios there are such where a tank might not have hit one or two mobs of a big pull with the same number of Flash/OP like the others.
Of course Quelling Strikes is not mandatory, but there are plenty scenarios where it will help to prevent fail and my real question is:
why would you even come here argue for not using it? Like really its literally for free.

"Not needed I just go all out if fails: tank is not worth his salt." hooray