You have a point, even with a good BETA, you never know how a person will approach a Quest. Many of the bugs that I have reproduced were passed to me by others and when I characterize the error, sometimes I have to ask why go at it that way- usually it's "I was exploring". None the less, we document it and pass it on to bioware feedback.
On the other hand, the rough launch and some of the glaring logic errors and missing and just wrong items say no BETA test was ever attempted, and only in-house compartmentalized tests were performed. There is no other explanation to miss some of these errors -none! I have never started breaking down code before I finish a game -here I have discussed mods just to fix errors to enable a finish. Oh, I know what quests and sequences to avoid and many pitfalls, but that is not the point.
My first game failure was in whispers when a red lyrium crystal dropped in an area where it could not be picked up. I understand the mechanism, the why it happens, and documented it as completely random! However, every loot or quest item or even rift events could and do see this problem with the proper conditions. When I found that bug the autosave was increased to prevent having to start from the beginning, but then profile errors causing corrupt saves -took a week just to define that set of problems! One person suggested adding buoyancy as a method to fix the error to critical or to loot in general to float the item to the top instead of getting stuck and I suppose that could apply to demons that get stuck also - it may happen.
I am not trying to be negative, but I can not be forgiving from my experience. QA was missing or just ineffective let's hope it's a temporary process problem.