You are right, its supposed to have a lot more utility than just combat related. It should indeed silence everything in there sphere.

Silence is great for corridors, rooms etc.

If you are out in the open field you will need to try and CC the mobs. I have shoved casters in my silence a handful of times and lock them down in there.

Sorcerers when they are added get an option to be able to cast spells without Verbal components, With the PHB there are a handful of spells that actually dont use verbal components but unsure if BG3 gives them all Verbal required.