Why?
To prop up prices? (likely)
To ensure survival after an event? (not likely)
Too much production, not enough sales? (I'm doing my part!)
According to the Washington Post, the cheese stockpile is so high because there's too much milk on hand for processors, and milk is more easily stored as cheese. Combine that wil school being out and cows being more productive, you get the record number.
https://www.wxyz.com/news/america-has-a-record-high-stockpile-of-cheese-at-1385-billion-poundsIf prices ever go down, stock up!