In practice, almost never. Internet arguments seldom result in both sides agreeing on a single outcome. Nobody is convincing anyone else of anything on the internet (most of the time).

Sometimes. Threads are archived. Questions closed but not deleted. New questions/comments disallowed. It meets a middle ground between absolute free speech and absolute moderation.

What I meant was people don't normally end a discussion, especially political, with one side admitting loss and agreeing that the other way right.