What is the proper way to handle questions about non-mainstream Islamic sects?

Question

I am bringing this question up here as a result of this answer to a question asking about a good way to learn about Sufism. The answer basically quotes a fatwa saying that Sufism is shirk. Setting aside the fact that the answer is just a copy-paste answer which makes it of minimal value, I think the entire concept behind the answer is a bad one.

The question asks about how one should go about studying Sufism, while the answer says that one shouldn't study it at all. I think this would be a valid answer if it were universally accepted that Sufism is completely unrelated to Islam; however, we know that this is not the case. Sufism is widely practiced throughout the Middle East and elsewhere.

This is a pluralistic site, so it seems to me that this question should be answered the way it is asked. Just because some mainstream Muslims do not believe Sufism to be proper does not mean that it should not be addressed here.

If such questions are not properly addressed, what stops Sunnis from answering questions about how Shiites should do something by saying "Shia practices are wrong. You should follow the Sunni practices"? Where is the line drawn?

EDIT

I downvoted this answer, but before I got to it, it already had 2 upvotes. That's why I'm bringing this question up. I really think the answer should be deleted as "not an answer", but clearly there is some disagreement so I'd like to understand the reasoning before I flag it as such.

EDIT #2

Related: Why Sectarianism is Ruining Your Site

Answer 1

You are correct: Answers should answer the question asked, and you should never let the number of votes prevent you from voting and/or flagging appropriately. We are a community moderated site, and one thing about community moderation is that a community is made up of different people. Different people don't necessarily agree on everything.

Just because someone else upvotes (or downvotes) a post doesn't mean they're right.

If you don't think an answer is useful (e.g. relevant) to the question asked, downvote. If you think it doesn't fundamentally answer the question, either flag or vote-to-delete (reputation permitting).

As for answering, one should keep the same guidelines in mind: Answers should be useful (e.g. relevant) to the question asked, and they need to fundamentally answer the question.

It doesn't matter if the question comes from a mainstream Sunni, or from a minority: an answer that is not useful is not a useful answer, and an answer that doesn't answer the question is not an answer at all.