Yes it's a communicative act. Communication can be bounced off others for social validation as you say, but can also be to oneself.

You'd still vent, if alone on a desert island, maybe to The Gods.

Ever hear yourself saying out loud, usually with expletives, something that you would "never say"? Listen to that voice!

That's communication of unconscious but frustrated thoughts. Sometimes it has to come out verbally because ones inner dialogue isn't strong enough due to social or superego suppression.

After you said it to yourself you feel better.

We are not the singular identities simpler minds suppose us.