I disagree. Most places I've worked, "I fucked up" is an acceptable response in an RCA as long as "I fucked up" isn't the end of the analysis. You shouldn't just be to throw your hands up and go, "well I guess nothing can be done then". People will fuck up, but you can do things to protect them from themselves, limit the blast radius, and make recovery smoother.

From my own life, I worked at a start up early in my career and dropped the entire production database. I was troubleshooting a production bug and had the prod DB open in one terminal window and my local DB open in another. I meant to drop my local DB and instead typed it into the prod terminal and that was that.

In the RCA we didn't just end at "I fucked up". The line of questioning went beyond that into what gaps allowed that fuck up to be possible which lead to action items around restricting access to production data to only those who need it as well as ensuring we had proper backups (thankfully, we did at the time) and ensuring we had runbooks on restoring data in the event that it happened again.