When I was 17, I was grounded by my father.

I pissed him off and that was my punishment.

I couldn't leave the house after dinner was finished.

I taunted him. Educated him. Told him that he hadn't been paying attention. That I disappeared into my room after dinner to read until I went to bed. My sister was the one who needed grounding or a curfew, not me. Told him maybe he should push me out the door after dinner and slam the door behind me and lock it.

He was out of ideas how to punish me after that bit of schooling. You can't punish a loner by restricting their social interactions.