Except that no one said the games didn't have any bugs. Perhaps you should go back and look at what was actually said.
I don't think there's ever been an RPG released by any company that was 100% bug-free. I'd say PB's games are in line with what's average. Gothic 3 being the exception of course.
You mentioned game-breaking bugs, I explained the ones in GI and II.
Gorath came back saying that that was multiple generations ago and I should forget about them and that PB games are mostly ok now.
Just went back to this thread
https://www.rpgwatch.com/forums/showthread.php?t=16990&page=5
Seems like Risen 2 actually also had at least one "game-breaking" bug (in "" because it's more really annoying than game-breaking).
Then of course there's Gothic 3, which is unmentionable, because Fluent said they were forced to release, but I didn't even mention that one until now.
So to me, PB games do come out with several game-breaking bugs, which they usually tend to fix after some time.
Again, love their games, but saying they aren't known for game-breaking bugs when their first 3 games all had them is a bit of rose-tinted glasses...
For me, the only game I have played from them without any major bugs was Risen I - from my perspective.
I do agree with you that the Risen series are probably on-par with other RPGs in terms of quality control, maybe even better for the amount of interweaving dialogue etc.