This is more of an extended comment than an answer, but I think it is quite important to clear something up, here.
We are not talking about consensus.
The Stack Exchange network is not set up to facilitate consensus-based decision making processes. Speaking from both personal experience and from having read theories of consensus, consensus is often hard to achieve. It takes long face-to-face conversations and a lot of work and energy. This is something that the Stack Exchange model neither provides nor facilitates.
Unless a network is still in beta and has fewer than 50 (20?) users, I find it particularly unlikely that consensus will ever be reached about anything that is even slightly controversial.
So this means that we're talking about majority-based decision making processes, and this inherently entails that some users will be unhappy.1
Now, what's the point of this discussion?
Well, the Stack Exchange model has been setup so as to facilitate the creation of communities, and these communities are, within limits, free to determine some of their own policies, practices, and oddities. Given that some of these policies will perhaps be controversial and given that the Stack Exchange model does not allow for consensus-based decision making processes, we have to accept that some users will be unhappy. So while this does not address the question about how "consensus" is actually determined (and I think David has already raised some good points about this), it is important to recognize that this is not "consensus" and just because some individuals (often individuals who do not participate regularly in the TeX.SX community, if at all) get upset, does not mean that we should immediately stop our practice and adopt theirs because the other way of doing things will not necessarily be any better. That is, it will just make other users upset.
- This is why comments like this, I think, are ridiculous. Why doesn't SO stop running so roughshod with new users? That obviously repels a lot of users. So SO should obviously stop doing that, right?! Of course not. There is good reason that they do things the way that they do.