Most of the answers are applicable for newer versions too. But if the OP never specified which version he is using, in my opinion, it is the fault of OP. Whenever a question is answered, the one who posts answer generally reproduce the problem by asking some questions from them like Ubuntu version, GNOME, etc. But if they don't answer that questions, then the question becomes unclear and are closed as unclear what you're asking. This might mean that OP never returned and at some point of time the question may become abandoned (unless it is highly rated).
If the OP never returned then we won't have someone to confirm the problem and what worked (if the problem is not widespread) until a person with similar problem visits the site and he have enough reputation to comment. And I strongly believe assumptions are avoided while answering.
If there's a answer of GNOME3 on GNOME2 then it would be less voted since at that point of time people were using GNOME2 and then shifted to GNOME3. If the same problem occurs on GNOME3, it may get votes if the answers work. But if it doesn't work, OP can always edit his question and elaborate what errors he encountered and why that question's answer didn't work. That's why comments always say "Possible duplicate of xyz" and need 5 votes to confirm (unless you are a mod). I've seen many a times people edit their questions if the suggested duplicate doesn't work and yes their questions are reopened.
To be noted: If the OP tried the answer on the target question (the question of which OP's question is a "possible" duplicate) and edits the question, the question appears on reopen queue where reviewers can think of opening the question again. This queue is visible to 3k+ reputation users.
PS: I crossed 3k reputation just a month ago and this answer was based on my personal experience. If readers find anything contradicting feel free to edit the answer or leaving a comment :)