Is this: https://wiki.mozilla.org/Identity/Persona_AAR a good post-mortem? Why?
It may miss the point that it’s very hard to enter a crowded market with big, established players. No matter how good your product is, people might not even look at it. Opportunities come from either needs or being compellingly better - the latter gets to be quite hard in a field where there are competitors, and the former really mostly exists in a market that doesn’t have products yet.