Different thing. "I told you so" is a smug, nasty statement. It wins no friends, and closes the ears of those most in need of it.
A postmortem is a clinical, reasoned, and scientific review. Everyone is on board, and agrees to abide by the results.
I worked for a Japanese company, for a long time. I made some colossal mistakes, during my tenure, and was told "That was, indeed, a mistake. We expect you to mitigate it, and not repeat it." Often, I would actually get more trust and responsibility, afterwards.
Yup, I tell my teammates, fix the error, not the blame. I refuse to find who did wrong. After an initial hesitation, suddenly everybody jumps to it and solves the issue.
Sometimes it's necessary to find who did something to find out what happened (maybe), but if the culture is good that's not a problem.
I've had no issues admitting mistakes at my places of work, and vice versa: "This is what happened/I did, which led to this. We fix it this way. What can we do to prevent it/similar things happening in the future?".
Edit:
People do most things with good intentions and for hopefully good reasons. When things go wrong it's usually down to unforeseen interactions or second order effects (or brain farts), and/or a lacking review process.
The person making "the mistake" is usually just the last person crossing a faulty bridge, and if it wasn't them it would've been the next person. It's not a problem identifying the person if everyone realizes we all want a sturdy bridge.
What you say makes sense in a good atmosphere. I work in a very toxic culture. Once people start blaming someone, their own blood boils with their rhetoric, and then it becomes a bitter fight.
I see it as etiology vs. teleology - rather than thinking "how did we get here?" we think "how do we get out of here?" The two are interrelated, but the second somehow gets things moving, and reduces resentment in toxic workplaces.
How do you, or how should anyone in a similar situation learn that actions have consequences?
I work for a large (not FAANG but spatially close) ecommerce company, and I’ve yet to see substantial changes or learnings after outages or mistakes.
I often find that wishy-washy post-mortems smear responsibility and deflect accountability. This doesn’t incentivize a change in behavior, and when people blindly get more trust, they often seem to simply repeat mistakes.
I think I’ve yet to master post-mortems and transforming “I told you so”s into improvements - I’d appreciate tips and ideas, thanks!
If you ingrain a culture of "actions have consequences" you disincentivize actions. This is why everyone is fine with letting nowhere projects run ahead, and adding to technical debt, or just keep on incurring running costs instead of cutting them.
"If I don't make a choice, it's not my fault".
It's much better to establish a culture of "try doing good things, and we're in this together". If you trust your colleagues and are good at recruiting, you'll get a lot more done.
I don't know if I have any specific tips and ideas for post-mortems as it usually... "depends".
If you work for an eCommerce company, then invest in mops. Hackers love eCommerce companies that fail to learn from mistakes.
Someone mentioned "bad corporate culture." In fact, the OP was really a sort of indictment of dysfunctional culture.
The Japanese are heavily process-oriented (not always a good thing). They have a consensus-based approach, where all stakeholders agree to a common set of rules and remedies before the meeting begins. If a problem is found, then the meeting doesn't end until there is a plan (and responsible person) for a remedy. Assigning tasks (not blame) is a goal. People are assumed to accept personal responsibility for their own mistakes. It's not the job of the meeting to do that (there's a common cultural mythology of responsible managers committing suicide, if they screw up badly enough. I never saw it, so I can't speak to its accuracy).
> I work for a large (not FAANG but spatially close) ecommerce company, and I’ve yet to see substantial changes or learnings after outages or mistakes.
I worked for Amazon and postmortems were taken seriously and done regularly - but things can be different in other teams.
If people warned about a risk in the past this would be noticed.
If nobody flagged the risk people would start asking why.
This is proof of bad company culture.
Doing post-mortems is important to learn what went wrong in the decision process and how to prevent it.