Because it makes people like you turn into whiny little crybabies.
Which means you post more to whine.
Which means that Rob gets more hits to his site.
Which makes the Google payment center compensate Rob more for the ads they put here.
Which makes Rob more likely to keep the board going.
See....it's all part of my carefully constructed plan to keep myself in Rob's good graces through that simplest of motivating factors: money.
As far as why Rob doesn't give you frontpage power, I don't know. That's between you and him. I might guess, however, it's because a picture of a shouting Hillary (that appeared in mainstream newspapers all over the country) might be annoying to some of her supporters (but no more annoying than, say, dissing "Star Trek" or "Doctor Who" might be to their fans), but is not as universally recognized as offensive in the US as a "fuck off" or "cunt" graphic. But again, that's just a guess. I'm on record as saying I thought you should have frontpage power. I've also told you in the past that I'd be happy to put up frontpage banners you make.
