Assigning (and accepting) responsibility is, I think, rather different from the "blame" that such retro's try to avoid.

You have to have a very safe work environment for that to happen. Otherwise, saying "I was blocked by person X" finding the wrong ears is a great way for person X to wind up on a PIP if the company's management is sufficiently inept.

I do miss being able to be honest at work.

Edit: rereading my comment, I realized I could have been clearer. What I really was getting at was the motivation: how do we help each other avoid the problem in the future, versus "everyone but person X can feel okay about what happened".