> The call ensures what, that you'll be more receiving to their grievances?

It ensures you truly understand what the crux of the grievance is and what they would like to happen to get it resolved, instead of being distracted by tangential points.

> That nothing is on the record?

If you’re already assuming malice before the resolution process even had a chance to begin, the conversation has little chance of being productive. Do you know this particular person? Have you interacted with them before?

> A lot of people don't want to jump in calls, ever.

Then say no! But being preemptively mad because someone asked is absurd and does nothing to fix the problem. The asker shouldn’t assume what the other person wants or doesn’t, they should ask. Which is what they did.

> Acknowledging the mistake immediately seems like a good start.

Yes, very much agreed. But you can’t take back what you did, only try to make amends. And that’s very difficult if the other party demands perfection while you’re still even trying to understand the situation.