Are these "15 boxes" what Trump returned back in early 2021? Since Presidents who have and use their private homes during their Presidency (IIRC, Clinton almost never used his home in AR, and OhBummer! seldom used his IL home) created documents while using their homes, many/most of those documents would have been kept and accumulated in those homes. IOW, probably many boxes of documents were moved out of Reagan's Santa Barbara ranch in 1988 and 1989, and similarly from GWB's Crawford ranch in 2008 and 2009.
Fauxrage over ordinary things most people don't know about is a common tactic by dishonest people, ranging from Dems to anti-Western-medicine activists.