This seems to give the edge to subject matter experts because generally (though not always) they tend to agree, at least on the kind of slightly out of date knowledge that is appropriate for reference works. Cranks, by contrast, have their own theory of everything which is peculiar to itself and inconsistent with every other crank theory of everything. The theory that the earth is flat and the theory that it is a cube are both opposed to the mainstream theory that it is roughly spherical, but they contradict each other too. Likewise for the theories that the moon is made of cheese, and that it is made of candy floss. Thus 3 experts can beat any number of cranks, so long as the cranks don't agree on anything.
However, neurologist Steven Novella makes an insightful observation here that brings this idea into question.
... cranks around the world have been able to form their own “alternative” community, publish their own journals, and have their own meetings. There is just one requirement in this alternative community – acceptance. All ideas are accepted (there is no chaff, all is wheat), that is except for one. Whatever is accepted by mainstream science is wrong [my emphasis]. That is “the one ring” of crank mythology, that brings all crank theories together and in the darkness of their community binds them together. Otherwise they are largely mutually incompatible. Each crank’s “theory of everything” is a notion unto itself, and is mutually exclusive to every other crank’s own theory of everything (unless there is some incidental overlap). So they get together, present their theories without criticism, and all agree that the evil conspiracy of mainstream science must be taken down. Of course, if any of them got their way and their ideas became accepted, they would instantly become rejected by the rest of the crank community as mainstream physics.Correct. My enemy's enemy is my friend, whatever my enemy believes. I have seen this effect in Wikipedia a number of times. Cranks unite to defeat the mainstream, orthodox view. Orthodox editors get blocked or banned. Cranks then war with each other, and get banned themselves. The orthodox editors mount appeals to the powers that be - the arbitration committee, none of whom have any expert credentials as far as I can see, and get unbanned. Or they just open 'sockpuppet' accounts and start editing again under a different name. So do the cranks, and the whole nightmare begins again. Another difficulty that Novella omits is 'mainstream' crankery. That is, bad science or quackery that unites its practitioners by financial interest. Homeopathy and 'Neurolinguistic programming' are good examples of this.
This would not matter at all, if Wikipedia were not increasingly used as a 'reliable source' by students, and even some medical researchers, as I noted in an earlier post.