I think a lot of users take self-answering for granted. What implicitly happens while writing a self-answer, is that we have a certain context which we implicitly place on other users, and then write the answer. This leads to locality of the answer. For example ,avoiding details makes the answer highly self-serving , because the intention of every answer , including a self-answer , is to serve the community, not yourself.
For this and this reason alone, the above answer should be flagged as an example of what can go wrong in self-answering. However, since it contains a generalization to the result, and a final answer, we can at least retain that part by attaching it to the end of the answer.
There is no need to ask for the opinion of OP, he/she has not visited the site for eight years, and therefore there is no opportunity to educate that person. Thus, we may entirely act in service to the community and do the honors of copy-pasting the post's material to the end of OP's question, and deleting his/her answer.
In general, we can do the same to self-answers which are self-serving .The moral of the story here is that self-answers still have to be community-serving, despite being written by the questioner him/herself.
EDIT : The change to OP's question has been completed , see here. The copying into the post of the self-answer has been done unabridged, and the answer has been deleted.