I maintain that original research should be permitted; coffee is a mix of science and art:
- substantiating references should be provided (and expected) for factually verifiable data: e.g., scientific facts; and
- "original research" or experiential recounting should be permissible for the "artful" aspects of coffee; e.g., techniques.
Hopefully expanding on @hardmath's answer, I believe that community input and verification is the mechanism to ensure a high quality of information, no matter what its source. I think there are three issues here: fact, art, and opinion.
If something is a verifiable fact: e.g.,
These facts can be (and indeed should be) backed up by a reference. If they're not there, they can be (and should be) added. If they're false, a countering reference can be provided, and/or the statement gets downvoted, deleted, edited, etc.
Art-, experience-, or technique-based questions and answers are legitimate; for example:
These happen to also be high-rating (10+ as of this writing), popular questions; but that doesn't itself make them legitimate. In some cases, these can (and should) be backed up with citations or references. Are those examples of non-fact, and are they legitimate?
Purely opinion-based questions and answers are generally not welcome, and I don't think this site should be any different. Except, of course, in meta sites, where (paradoxically?) opinion is largely the only topic being discussed.