Depending on what broke, it's entirely possible for ACARS to work and not voice.

Had a maintenance delay on a 73G this morning for a non-functional intercom. Cockpit to front station, no problem. Cockpit to rear station, worked fine during preliminary checks but failed as we were pushing from the gate.

Most of the system worked, just one handset being offline though was enough to hold force a maintenance delay. I don't believe any of those intercoms are deferrable, so it had to be fixed before we got in the air. Thankfully, it only cost us about 45 minutes.

So yeah - to your point - if it's the actual transmitter or receiver that's broken, I'd think we may have a common failure. But there's plenty of other bits & pieces such that ACARS could work while voice was dead.