When I posted this, This was a partial answer. And yes, it would likely have been better as a new question. Be that as it may, The aforementioned post clearly shows a commitment to improve it as the edit record makes abundantly clear to the casual observer.
In this case, it's unclear whether the answer related to the version of Ubuntu asked about or a more recent version, but that information could have likely been easily obtained (considering the obvious commitment to improve the answer). The Nvidia driver versions mentioned all appear to have been released recently with the oldest version released about 8 months ago.
Since the Answer the question section of https://askubuntu.com/help/how-to-answer states clearly that "Any answer that gets the asker going in the right direction is helpful, but do try to mention any limitations, assumptions or simplifications in your answer. Brevity is acceptable, but fuller explanations are better." I think it's safe to say that this was an honest attempt to help on it's way to becoming a complete answer, and I hope we didn't drive away someone who was Truly Eager To Help.
It might even be fair to say that all answers are partial answers as they can be edited and improved when new information becomes available, updated to cover new versions, etc. I do this fairly often myself.
Edit:
Guidelines are an important part of maintaining a cohesive policy and it's important that we are all at least trying to accomplish the same thing (improvementWhich I think is improvement of the site as a whole)
IfThis is a great question and if as you surmise, this a holdover from back when we would close questions as duplicates of other unanswered questions (before my time here, so I wouldn't know) and we aren't going to accept partial answers that contribute the results of your research and anything additional you’ve tried then clearly the guidelines should be re-written to reflect this new more stringent approach so that users attempting to follow the guidelines don't get blind sided by an unwritten policy.
Clarity of instructions is required in order to get desired results so lets be clear about what we want so that we can obtain it.