Keeping things vague for a purpose and being unclear about what to say are two different things.

In the world of fiction, dialogue is the lifeblood that pumps through the veins of every great story. It’s the invisible thread that weaves characters together, propels plots forward and breathes life ...

The vast majority of scripts contain dialogue. It's likely therefore that your (yes, you, reading this - your) script contains dialogue, too. Now, of course, some actors are prone to ad libbing around ...