How can I add "dislike" button?

I agree (with the sarkasm). But the challenge is to find out what exactly people want. It’s a challenge because “people” implies diverse needs and opinions and you need to find a way to decide which path to take. This is why I quoted from “How does the Discourse project work”, not because I necessarily agree with all the criteria layed out there but because this is how the Discourse project works.

I wouldn’t say that “complaints driven software development” is much about "people knowing better than others. If were referring to the Discourse philosophy, then I wonder whether you mean to imply that there shouldn’t be any philosophy or whether anyone should be allowed to change it at will or whether you just wanted to call the “anti-downvote policy” into question.

If the latter is the case (which was how I understood you) you simply have to be aware that this goes very deep into the basic philosophy of Discourse, and to point that out was the only point of my post.

Although I do agree that the tone on this forum is not always as friendly and argument oriented as it could be, I would say that your request has been treated with much goodwill here, in spite of it going against the Discourse philosophy. The point of disagreement is probably in just how much an effort a community should make to assist a member in achieving something they themselves don’t really believe in.