Here's my personal opinion:
1. Reputable Sources should always be used.
I've written about this a lot, so I'm just going to quote from a relevant History SE Meta post:
Is this site an academic source?
My teacher recently rejected the idea of me using this site for a research paper, and I was wondering if you would think that this site could be considered a source.
Your teacher was right to do so. This website would probably be a bad source to use as a primary reference in a paper. Any random moron in the world with internet access is free to post an answer here. (For exhibit A, click my name below...)
However, if there's something that has you stumped in your research, I'd think it would be an excellent place to try to get your questions answered. Good answers here should be sourced with hyperlinks, so it would also (hopefully) be useful for digging up other references that are usable. Use the references we supply to help jump-start your research.
For anyone who is trying to do actual research, answers without sources are useless. I'm not even going to talk about how answers without sources are often inaccurate, but I've noticed that people who know where they got their information from usually don't misremember things or post incorrect facts.
Those two reasons are why, in my opinion, answers without reputable sources are essentially fabrications, and should be removed because they don't even answer the question. Of course, this isn't the site policy and many people disagree with me.
If you want to do something about it, leave a comment on unsourced answers asking for reputable sources. This is what I do, and here's the comment I leave:
May I encourage you to cite reputable sources (e.g. not wikipedia)? Doing so makes it easy to know if your answer is right, and also provides starting points to users who would like to learn more about the topic.
(You can speed this process up by using something like AutoReviewComments.)
2. Use both academic and primary sources.
If possible, use both! I do this in many of my answers. They are both reputable sources.
To elaborate, this site is in a weird position academically, because mythology is a hybrid between literature, history, anthropology, and religious studies. Some questions are better answered with an academic study, some questions are better answered with a close reading of the text in question, and some questions are best answered with a combination of the two. Use your judgement.