Answers are not just for the OP. Many others will come here asking the same question, and they will have different backgrounds; it is preferable to collect all relevant answers in one place. Unless you are proposing that identical copies of the same question, the only difference being that they were asked by people with different backgrounds, should not be closed as duplicates of each other, because you think they should be getting different answers? That sounds too complicated to keep track of, and too murky to figure out when people have "comparable" backgrounds (this all assuming we get any response from them regarding their background at all...).
Moreover, advanced answers benefit other users who will learn something new about the question and its connections with the many topics in mathematics that the OP has not learned yet.
Additionally, while we have over time honed what is (in my opinion) an excellent welcome comment, which explains how it is in the OP's best interests to share what they've tried or thought about, ultimately the responsibility lies with the OP to keep their academic honesty. After all, this is the internet - we really have no idea who the OP is, whether they're telling the truth about something being homework or not, etc. That's why the welcome comment mentions that people will still help even when something has the homework tag; attempting to shame them for asking homework questions will only cause people to use further secrecy and dishonesty, whereas if we explain to them that we are (approximately) okay with it, they are more likely to provide us with an honest answer about whether it's homework, answerers can take that information into account as they see fit, and the OP is more comfortable in general (this is how I currently see it at least).
Also, while I am fine with expressing one's opinion that answerers should not provide complete solutions to homework questions, that is something I would also prefer to leave up to the individual answerer. What even comprises a "complete" answer will vary with the OP's ability as well; what is an opaque hint for one person will solve it entirely for another. What would you have the moderators, or the community, do about this?
One thing I feel quite strongly about is that, if someone feels that an answer gives too much away, please do not flag it for moderator attention. Over the past month (for example), there have been approximately 50 flags per day. This is not an issue that requires the intervention of a moderator in any way and I would prefer to keep flags reserved for those issues.
I appreciate your zeal for encouraging people to not give away full answers to homework questions, and I support anyone commenting on such answers (or even downvoting, if you feel it appropriate). However, this seems to me to be the solution that has been effect, by default, this entire time; nothing to change there. I agree that your posting on meta about it helps to raise awareness, but I don't see this as being a long-term solution - it seems rather pointless to continually debate something solely for the purpose of it being visible.