Obsidian Entertainment developed the game, not Bethesda. Bethesda published the game, they had nothing to do with this game's development process.
That’s true, but the publisher is in charge of the quality assurance (with an internal or external QA team), so you have blame them. So maybe the QA didn’t do their jobs, or this game beta was so unplayable that they achieved at least the current state or the producers were aware of the problems and decide to solve these issues with patches. I guess their marketing department had a also a certain role to stick with the planned release date. Whatever it was, it doesn’t look good for neither of them.
Obsidian is a decent company with, imho, a horrible horrible programming department. Every game engine (Odyssey, Auroura, Unreal and now Gambyro) they got their hands on turned pretty much into a buggy bloated mess. These engines have already their problems in the first place, but it seems once they fiddle with it at Obsidian it reaches a new low or high however you like to see it. Even if Obsidian may have their own little QA team, it seems they test only the changes in the current milestone and never the game as a whole.