Stack Overflow has seen a substantial decline in traffic over the last year that appears to be accelerating. https://observablehq.com/@ayhanfuat/the-fall-of-stack-overflow
If SO supposed to be wiki, then why there no clear way to update the answer with new information? Why only the person that asked the question can mark answer as correct? Clearly some person with more expirience should have possibility to mark answer as correct.
Depending on your reputation, you can edit the answer / comments of others. It’s usually not recommended to change the context of the question or the answer but you could. Those update will be reviewed by other if needed. As for the correct answer, you can always upvote the answer you feel is the correct one, which is kind of a community way of selecting the correct answer.