It's not uncommon to find new users editing or commenting on their questions with something along the lines of "Update: I solved it by Xing the Y with Z" instead of posting their solution as a self-answer. This is an ongoing issue that I think isn't helped by the 8-hour delay for new users (<100 rep) between posting a question and self-answering.
This delay has been in place for several years, though not having encountered it personally, I only learned of it this morning. The message shown to new users attempting an early self-answer is:
Oops! Your answer couldn't be submitted because: Users with less than 100 reputation can't answer their own question for 8 hours after asking. You may self-answer in [ N ] hours. Until then please use comments, or edit your question instead.
Emphasis mine. So, what action is this message specifically recommending? Before you answer, make sure you've got your "new user" hat on, because only new users are seeing this message at all. And when they see this message, it's because they clicked the "answer" button, which - despite its frequent misuse - suggests that they may actually be trying to answer the question. So it should come as no surprise when a well-intentioned new user gets the wrong message:
The error message from Stack Exchange told me to try just editing my question to include my answer...
The purpose of the feature is explained (or intuited) at greater length in this answer from Cody Gray, which notably includes the following:
If you want to respond to another user's answer in order to to ask for clarification or additional help, you should leave a comment (new users can always comment on their own questions). If someone asks you for additional information, you should edit your question to include that information.
That's a good explanation. It's clear, brief and identifies specific uses of comments and edits. If prompt self-answering is a trigger for the system to step in, apply the brakes and deliver some important knowledge and if we've identified this as an opportunity to educate new users, that's the type of message they need to see - not something akin to:
Oops! You couldn't drive that nail because: Users who have built fewer than 10 birdhouses can't use the hammer for 8 hours after opening their Acme Birdhouse kit. You may drive a nail in [ N ] hours. Until then please use the screwdriver or chisel instead.
So here I am, just back from the hardware store with a bag full of nails, and that screwdriver looks pretty sturdy...
I'm not the first to point this out as potentially confusing; Benjamin Gruenbaum said much the same thing in a nice answer last year to What to do when OP answers his/her own question in an edit?:
A user reading this might understand "You should edit your question instead of posting a self-answer". I think a better phrasing is needed.
Well, Benjamin, I agree - so here's a feature request. Let's revise this message so that it doesn't mislead new users into thinking that self-answers are ever appropriate to leave as comments or edits to the OP.