I'm going to go outside the box, as the saying is these days, and give an answer about fundamentalism generally. Most people just hate the idea of unchangeable "fundamentals," while fundamentals form the basis of so many things, far more than in theology. Obviously some people somewhere do strongly support fundamentals, but this will inherantly be in only one area. Thus, Christian fundamentalists are non-fundamentalists about the U.S. Consitution, environmentalism, and the 'peace movement,' even though each of these does have a strong relation with certain scriptural principles (but are secondary, of course, to the fundamentals of the gospel). The ACLU and like organizations seek to be fundamentalists on the Bill of Rights, and thus are very anti-fundamentalists about their own religious beliefs (many do have religious beliefs), the fundamental principle of warfare ["kill or be killed"], and the fundamental of capitalism [anything goes as long as it's profitable]. Environmentalists just replace 'fund' with 'environ' and place a total priority on green trees, wildlife, clean air and water, to the extent that business profit, conveniences, and religious goals (unless they incorporate environmentalism) must all take a back seat. Fundamentalists of any kind also tend to believe "the end justifies the means" if it the 'end' is one of their fundamentals. Thus, Christian fundamentalists think fudging on the US Constitution's "no law respecting [their] establishment" can be stretched; the ACLU thinks 'equal opportunity' does not preclude "affirmative action"; and environmentalists drive their gas-guzzling SUV's all over the country to push their agenda.
There are, of course, "fundamentalists" in less important endeavors, such as sports. Vince Lombardi had a reputation for preaching "fundamental football," which means he drilled his team to run the same plays hundreds of times in practice rather than drawing up new strategies to deceive, and he did quite well against the more 'razzle-dazzle' coaches like Tom Landry and Sid Gillman. Woody Hayes taught "3 yards and a cloud of dust" and disdained the forward pass and won big that philosophy. Yet he was degraded as "colorless" and too unchanging... because people don't naturally like fundamentalism, even if it's shown to work. People like "flashy," "colorful," "imaginative," et al; new ideas, new approaches. Science fiction fans dislike the fundamentals of science-- thus, science fiction, where the impossibility of faster-than-light travel is ignored.
But I think it's also possible to be the paradoxical fundamentally moderate. If being 'in the mainstream' is the most important element for you, you could be so characterized. All in all, people tend to be fundamental about what's most important to them; therefore anti-funadmental about everything else. So the fundmentally moderate hates anything "extreme"-- terming those who support any such views as "fundamentalists," in this case a term of derision.