I'm glad to see this question, as I was just going to ask it myself. This has become a pet peeve of mine. I strongly believe that we should allow questions about personal finance even if they are not directly about the asker's personal experience. To me, the "personal" in "personal finance" means questions should be related to decisions made by individuals about their own individual finances, not necessarily decisions made by the questioner about his or her own individual finances.
There are two main reasons I think this. First, there are many questions not about the questioner's own finances that we do and will continue to accept, and there is no clear, reasonable basis for separating them from ones we wouldn't accept. Second, we do not need to use "it's not you" as grounds for rejecting wild hypothetical scenarios, economics questions, etc.; when we need to, we can reject those questions on the basis of their actual content, not who asked them.
What I mean with my first reason is that "personal finance" obviously includes decisions about people other than the individual asking the question. Consider, for instance, questions about a spouse's finances, children's finances, siblings' finances, parents' finances, elderly senile parents' finances, a friend's finances, a poor-with-no-reliable-internet-access friend's finances, a roommate's finances.
There are lots of valid reasons to ask a question on someone else's behalf. The person in question may not have the ability to ask the question themself. The questioner may be trying to help someone close to them who, for whatever reason, cannot or will not take the time to ask. People don't waste their time asking questions that they don't care about on some level; if someone asks a question about someone else, we should assume that they are asking it due to a personal connection with that person. This question is an example of a highly-voted question that is really about someone else's finances: the questioner is asking about how to help his friends who have poor financial habits, and the (good and upvoted answers) are largely about how to help these friends solve their problem, because the questioner is not in any real financial trouble himself.
The same applies to questions that are hypothetical but may become real in the future. If someone, for instance, asks questions about how to handle issues that may arise when their old and frail mother passes away, are we to refuse to answer until the death has actually occurred? If someone asks whether it's a good idea to buy stocks when they are down, are we supposed to wait until stocks are actually at a 10-year low? No. We should trust that people ask questions that are relevant to them at the time that they ask them.
My second reason is that rejecting questions based on who asks them doesn't really gain us anything. A question like "Is a graduate-student stipend taxable income" is good regardless of whether the person asking it is a graduate student receiving a stipend, because many graduate students receiving stipends do exist and may find the question helpful. A question like "Why won't Switzerland join the Eurozone" is not about personal finance no matter who asks it.
As for hypothetical scenarios, we don't need to reject those on who-asked-it grounds. A question like "What is the safest investment in the event of a meteor strike" has no real answer, even if it asked by someone who genuinely believes a meteor will strike the earth. Questions that are hypothetical but realistic should be accepted, because even if the questioner is not facing them, real people may indeed face them (or may have faced them in the past). For instance, when politicians make noises about changing financial laws (e.g., Obama's recent aborted proposal to eliminate 529 plans), I would consider it reasonable for someone to ask if there are financial actions they should take if the law in question is passed. It's hypothetical, but it's a reasonable thing to consider.
A final point is that, since we have no way to verify that anyone actually has the issue they mention, trying to restrict questions on this basis is pointless. If the person who asked the celebrity banking question edited it to add "P.S. I am a celebrity but won't say which one to protect my privacy", does that mean we should then answer it? If someone asks the meteor strike question and says "P.S. I'm asking because I looked up at the sky with my telescope last night and saw a meteor approaching", would that change our stance towards the question? As long as the questioner can provide enough plausible details to admit of the possibility of an answer, I think we should assume they are drawing the details from their experience rather than their imagination. There is no way to really know.
So basically what I'm saying is that I think "personal finance" is a topic, and the topic restriction is a restriction on questions, not questioners. Questions that are about personal finance are on-topic even if the person asking the question is not the central party involved, as long as the question describes a situation in which there would be some central party making a personal finance decision.