Being held accountable is irrelevant. If what people want is someone to be accountable, people will get scapegoats.
The key difference would be that when acts happen that defy the needs and expectations of society that those actions end.
If Keith Alexander was blamed for acting without authorization and imprisoned for treason and then NSA operations went quietly on their way again, that wouldn't necessarily mean anything.
If on the other hand, there was no punishment doled out, but instead any apology was given out and the PRISM program and similar were dismantled, and a new intelligence system were built in its place with support and approval from the public. Maybe something with proper auditable checks and balances, something with less risk to the public. If that was the case, even if nobody was punished, the situation would improve.
Calling for punishment or vengeance will satisfy emotions. It doesn't do anything to change the status quo. I'm not in the US, but if I were, I wouldn't be calling for the President to be held accountable, or anyone else. I would be calling for change of the laws and processes that I felt were violating my rights.
I think this is especially true in a system as complex as government. There is no one person truly responsible for these systems. So to focus on punishing a person is meaningless. People can be forced to do things despite the potential punishment. People can have decisions made by more powerful people attributed to them.
In the end though, it is more important that bad behavior stops than it is that we exact retribution on some person for it happening. If the latter happens without the former, it's worse than meaningless.