It amuses me how the low limit nature of Excel has affected the ecosystem around it. Apache POI, which is a popular library to operate on Excel files, has a weird 4GB limit [1] on uncompressed file size.

throw new IllegalArgumentException("Max entry size is bounded [0-4GB], but had " + maxEntrySize);

[1] https://svn.apache.org/viewvc/poi/tags/REL_5_0_0/src/ooxml/j...