To answer your question OP, Richt is accountable for the Offense, always has been always will be.
He's the playcaller, play developer & the de facto QB coach because his son who isn't even 30 years old yet has very limited experience.
Our Offensive identity is big play or bust. If we don't hit on the Deep Ball we typically struggle on Offense because we're very inconsistent running the ball & against actual Defenses the intermediate passing game becomes nonexistent.
Everyone always says "we have guys running wide open, the offense is fine we just need a QB!", what you're basically saying is the Offense will be drastically better next year, but how can you assume that if the 3 QB's we got hardly ever play, in fact only 1 of them has ever taken a snap in more than 1 game. So, if I'm to believe the only thing that holds us back is a better QB & if I'm also to believe that QB is already on the team then wtf is taking so long to actually see it happen?
To me, the problem is this offense is specifically constructed for Rosier & none of the other QB's really work in it as of now because it's based around a guy that can only make certain throws against P5 competition. We really struggle run blocking against good Defenses which forces our QB to have to throw way more times than he should.
The job of an OC is to find the weaknesses of the Defense & exploit those weaknesses by creating mismatches. They put the playmakers in the best position to attack & move the ball while minimizing mistakes. We have to play around our deficiencies as an Offense, which means if we can only be good if everything is perfect then somebody is not doing their job.
If you think we can never expect to be good until we have an OL full of 4/5-star lineman who are all Juniors, then you're going to be waiting for long long time, because that's not going to happen anytime soon.
Can't keep making excuses, either Richt is this great OC that is above reproach or he's not. And if you're saying "next year with Jarren...", then ok... Keep pushing those goalposts but the clock is running out those excuses.