Realistically speaking, postgresql wasn’t handling a failed call to fsync, which is wrong: but materially different from a bad design or errors in logic stemming from many areas.

Postgresql was able to fix their bug in 3 lines of code, how many for the parent system?

I understand your core thesis (sometimes durability guarantees aren’t as needed as we think) but in postgresql’s case, the edge was incredibly thin. It would have had to have been: a failed call to fsync and a system level failure of the host before another call to fsync (which are reasonably common).

It’s far too apples to oranges to be meaningful to bring up I am afraid.

NATS allows you to fsync every calls, it's not just the default value.