My idea is that a generic new contributor (you can think in yourself person, or other with distinct background, motivation, circumstance, perspective, experience, need,...) should to think what is his/her motivation to ask in this site. If this new contributor is, say us, a PhD student or a professional mathematician it is a proper context, the scenario is clear in this case. For the other cases there is generosity and flexibility, limited (for example if a contributor got many downvotes, if I am right, can be banned
temporarily to ask more questions until this new contributor earn more upvotes than downvotes).
What am I saying? I'm going to expand my introduction, but I think that it is clear, at least for me: I know my motivation to ask in this site, and I know how much activity, or reults can I expect from my interaction with the site.
First that it is public the information from the encyclopedia Wikipedia about an overview of this site from the article MathOverflow. I'm sorry if I am rude or toxic in your question, that I am saying is that I think that the questions of the site Mathematics Stack Exchange typically are from students, and this site MathOverflow has a different scope. As aside remark in this paragraph is that thus is better don't cross-post questions in both sites to avoid misunderstandings.
Secondly that I think that it is a problem concerning to each new contributor: that the new contributor need to take resolution of him/her situation to face the career as a mathematician. Again the case of the professional mathematician or the PhD student is clear and I and stop here for discussion of such scenario. The other case, in general, is about a person that, being alone and without an advisor or perspective to do a professional caree as mathematician in the next future, wants to ask in this site. For example I am not a professor and not a young student, other examples of this case can be amateur or mathematical enthusiasts that after a different professional activity (imagine for example a programmer, a mathematician teacher of high school, or a mathematician working in the industry...) want to research in mathematics and or contribute in this site MathOverflow (the last case is of the young students that is my third paragraph).
The last thing is that I think that the situation of students who have not finished their studies is improper. With the word improper I am saying that the situation of the young students of a degree in mathematics is, of course, honest but isn't the more suitable (I try that next paragraphs will emphasize each other this my opinion):
Mathematics or physics studies are very difficult, these studies qualify special professionals, who are useful and cotized in the industry, but the personal price to pay is to stop thinking about mathematics. And being a student it is hard to think that one will stop thinking, in the near future, as a mathematician, that one will never have a future in which can discover mathematics.
They, the young students, are immersed in their education as mathematicians, but the most of them will never be mathematical researchers: a great percentage of these students will be working in next years in the industry and they never research in mathematics, with the exception that some research work is required to close his/her degree/curriculum in mathematics. It is plausible to think that after a few decades of years (10-15 years) they will have forgotten part of their knowledges.
As conclusion, when I was a student I did not find/met my classmates trying to send proposals or answers to problems published in mathematical journals, or small remarks or articles in mathematics. And I'm not saying it in a sarcastic way. Because I think it is a legitimate and necessary thing for students before ending their studies in mathematics, even if they fail in a humble attempt. The research proficiency or ability, at any level, is obtained by being a researcher. It’s a sad road, a paved road with sacrifice.