Table corruption may not be 'acceptable,' but that doesn't matter. Even if your software is perfect and has no bugs, it cannot account for issues at the system and hardware level. Backups and redundant systems exist for a reason. I've have data corruption in a PG database before. I don't remember the cause--I think it was the filesystem rather than Postgres that was at fault--but it still happened and I had to deal with it.

Obviously the situation being discussed here is corruption specifically because of the database software. If a comet destroys the entire datacenter and the data is lost, nobody is going to blame Postgres for it.