Stories fester when they're at home, you know. They need a wild ride in the mail or through the phosphors and then they like to wait on desks or in editorial hard drives where they can chat with other manuscripts and drink too much and party. Sometimes, when they've just come back, they're lively and have lots of things to say to the other stories who've been stuck at home, but they quickly grow morose. Then the festering begins, usually with some discoloration, and then the smell. If that doesn't get your attention, they can ooze like nobody's business.
It's easier to avoid the whole festering thing and keep them in circulation. Everyone's happier that way.