This has been the most common question I've gotten. I'd say partially it's my bias as someone who works in recommender systems a lot. Many/most common statistic

This has been the most common question I've gotten. I'd say partially it's my bias as someone who works in recommender systems a lot. Many/most common statistical problems have a compact matrix representation (e.g., systems of linear equations). Finally, everyday matrix decomposition tasks like SVD.