In a sense, it was ultimately Night Light's fault. He was the one who wouldn't let Twilight Velvet throw out Shining's old toys, remembering his own lost collection of meticulously sorted baseball cards.
Granted, by that logic, Shining was the one to blame, swearing he'd come get his stuff out of the basement "next weekend" for several hundred weekends until disaster inevitably struck.
Of course, everyone agreed that the real culprit was the wild Equestrian magic that found its way to the basement and struck as said disaster.
An entry in Thought Prism's Ultimate Crackshipping Contest. No familiarity with Chibi-Robo! is required to enjoy this story.