I'll tell you why. Because troll moderators have taken over the site and are trying to subvert it. Because the IT readership that used to visit Slashdot has been bleeding from the site in the last few years, leaving behind the more extremist posters. Because if you say something that those posters don't like, they abuse the moderation system to drive you off the site rather than reply and explain why you're wrong.
The latest thing is to accuse absolutely everyone of being a "shill" so that others will follow along and do their dirty work. My post didn't go down to -1 Flamebait until someone else accused me of being a shill and got modded +5 Insightful (!). Because of the default filters, +5 comments are automatically expanded while less than +2 is collapsed, so now every moderator reading the comments for the first time will see that post first and likely not even read what I wrote.
CmdrTaco promised a new moderation system for years, and it never arrived before he left the site. This limited moderation pool concept is terrible. It makes it so that a single point in either direction has a drastic effect on karma and effectively restricts people from posting something that's unpopular, even if it's legitimately true.
This is off-topic, and so I'd be justified in getting downmodded for this, but since my karma is getting completely destroyed right now anyway, I may as well post it before I'm limited to two posts a day. Thanks, Slashdot. Thanks, troll moderators.