Despite being a strong believer in it, I've worked at places that did blameless post-mortems and it was sometimes frustrating because remediation often felt like a second-class citizen. Remediation is often much more difficult in these environments because systematic changes can obviously much more complex than "fixing" an individual's behavior.
If someone pushes the big red button accidentally I'm fully on-board with the "well what led them to push it and why were there no safeguards?" but it also kinda sucks if you spend so much time on that conversation that there's no time left for "ok, who's going install the confirmation screen for the big red button?"
Sometimes the "remediation" was even just "well, that's just the way it is and we can't do anything about it easily, but hopefully the post-mortem itself will serve as a way to inform people not to push the big red button" which is obviously frustrating because memories are short and people come and go quite frequently in the tech industry.
Anyway, and this might be obvious to some, but remediation is important and sometimes incredibly difficult in these environments. Adopting such an environment requires a commitment to actually fixing the systemic issues. It can sometimes feel more frustrating than "blameworthy" post-mortems especially if it's the same individual(s) over and over again.