Because they're playing an old Jedi mind trick on us, without even having a connection to the Force.Skepticism and Moral Relativism are simply sophistries meant to undermine somebody else's worldview, and while your victim experiences existential Blue Screen of Death, you impose your own worldview.
@TDK - That's about it. The funny thing is that quite a lot of people really do believe that they themselves are skeptics! (http://www.skeptic.org.uk/) I'm not so sure about what moral relativists imagine they are up-to.
I don't have much of an objection to a limited skepticism in regards to newage or nonsense regarding UFOs, and used to follow the "skeptical movement" before it got derailed by New Atheism and I'd imagine Atheism+. But this limited skepticism is really just not being overly credulous of extraordinary claims, which falls under common sense, not revolutionary philosophical insights. I suppose internalizing the scientific method is what they're essentially all about.As for the "moral relativists" they're always, not almost always, but always some variety of leftist. Actual Nietzscheans are so rare outside comic book super villains, that they may as well be a topic for the aforementioned skeptics.
If one displays actual skepticism in any public setting one is attacked by the gatekeepers (e.g., 'mainstream media'); and moral relativism seems to me to be oxymoronic. Therefore, even if some frogs notice the water is boiling, as long as the pot is covered the frogs have no way of escape intellectually (e.g., through true skepticism in a western scientific sense, or through moral and/or ethical comparison).