Because here’s the rub, and it’s a little provision contained in the site’s Terms of Participation:
“The White House may elect to respond to petitions at any time, including those that have not crossed the first or second threshold.”
Translated, that basically means the White House will respond to your petition if it gets over 25,000 signatures in 30 days, except that they might take months to respond to a particular petition, if that, and also they might respond to petitions that haven’t crossed the threshold if they deem it important enough. Which, again, all basically boils down to “we’ll answer what we want to answer.”
Maybe the White House website has become less about petitioning the government to seriously address policy, and, in the spirit of the Festivus season, perhaps it’s simply become nothing more than an airing of greivances.