Post-mortems start being important when users rely on your stuff and stakeholders want an explanation for a problem. They also want to understand if you understand the problem, if you care about the problem, and how is it not going to happen again.

If you say "we fixed the issue" 10 times in a row for the same issue, you lose credibility and the organization will look to replace you.

If a problem in your product is affecting my ability to do business, you either give me a proper explanation or I will find a replacement product.

The prototyping phase of a product is just an engineering honeymoon, it does not last forever.