@DavidStratton It's not discouraged and there is a mechanic to be able to just post your own answer right with your question so I'd say it's mechanically encouraged
as far as it's appropriateness, well that's going to be entirely case by case
one more note on the above. Remember the self accepts are mixed in by vote order rather than pinned at the top like a normal accept. That means that if there is a better answer but hte OP is stubborn about theirs it won't be given preferential treatment.
@David Along those lines, i think the ones that are really problematic are so because of the nature of the question and the way the content is framed and they would be problematic no matter who asks/answers.
@Wikis He copied and pasted it. If you read the conversation, you'll see he'd been confused about who said something, then found it was you, then copied and pasted your comment to demonstrate that it was you.