There were rules. Was there ever a manifesto? Not exactly, but Ezra Koenig at least gestured toward one. The idea was to establish some stylistic guardrails, to prevent Vampire Weekend from defaulting to easy rock-band tropes and to set them apart from their peers. As Koenig explained to the Denver alt-weekly Westword in 2008, the notion that band members were forbidden to wear T-shirts onstage to maintain the group’s preppy image is strictly apocryphal. But “no trip-hop” and “no post-punk” were real. So was “no distortion.”