I'm curious about pickling wild edible mushrooms, but it can't get approved for this. Allow people to add pickling techniques for obscure things.
First, I'd like to note that our site's rules and what I'll say below absolutely does not mean health/nutrition questions are bad questions, or that people shouldn't want to ask them and discover the answers. It just means this isn't the place for it.
Roughly, our rule is that in order to be on topic, the key knowledge necessary to answer a question has to be about cooking. (There are of course additional restrictions, like avoiding overly broad or subjective questions.)
So for example, if you want to pickle mushrooms in general, or if you want to know how to make your pickled mushrooms less mushy, then all of the key knowledge to answer is about cooking, so it's on-topic. But if you want to make a medicinal mushroom extract by pickling, then the key knowledge to answer includes medical knowledge, so that's out of scope.
I think this rule has served the site well, and the reasons for it still apply, so it should not be changed.
The issue with health/nutrition questions was never that they aren't anything to do with cooking. It's that they are about health/nutrition. To summarize:
- Difference of subject. Cooking is fundamentally different from health/nutrition. Yes, what we eat affects our health, but the actual subjects are very different. StackExchange sites are focused on specific topics, and our chosen topic is cooking, not health/nutrition.
- Missing expertise. Our site is built around attracting people with cooking expertise. We do not have a similarly strong community of people with health/nutrition expertise, trying to build that would be extraordinarily difficult (to the point that people have tried to build it as its own site and struggled significantly), so we simply can't handle the questions.
- Likelihood of misinformation. There is an awful of unsupported health/nutrition information out there, and an awful lot of people buy into it. This makes it incredibly difficult to uphold quality standards. Even requiring citations from scientific journals isn't really sufficient; studies are frequently misinterpreted.
- Likelihood of debate. Worse, a lot of that unsupported information is contradictory, and plenty of people are ready to debate to the death in favor of their various contradictory views.
This isn't a complete list, but it's enough to justify our rules. And none of this is hypothetical. We've seen it all on older questions before these rules were settled upon and enforced, and periodically in comments even with the rules.
Much of that also applies to other tasks that are done in the kitchen but which aren't for cooking. If you want to wash your hair in the kitchen sink, or use your oven to bake glaze onto your sculpture, that's great, and at least it's less controversial, but it's still not our subject or our expertise, and I don't think it should be on topic here.