Neccesity leads to JIT, but also sustained surplus. If the winters are mild and food can grow year round, why bother stockpiling? If any widget can be obtained quickly and cheaply, why spend the extra effort to maintain inventory? If I can always buy ground beef at Walmart, why should I keep a winter's worth supply in my freezer? These practices are fine as long as the underlying assumptions remain valid. If one suddenly finds that they can't reliably buy toilet paper on demand, there is an incentive to hoard it. And that's exactly what happened.
[1] While it has taken on a somewhat different meaning in recent times, the early meaning of the word was 'to store and preserve for future use.' https://www.etymonline.com/word/hoard
[2] https://www.jstor.org/stable/44687105
[3] https://nchfp.uga.edu/publications/nchfp/factsheets/food_pre...