The benefits are that ASV / USV files are trivial to parse with simple string splitting since you don't have to worry about nesting and quoting.

Here's an example of what a USV looks like:

Folio1␟␞ Sheet1␟␞ a␟b␟␞ c␟d␟␞ ␝ Sheet2␟␞ e␟f␟␞ g␟h␟␞ ␝␜ Folio2␟␞ Sheet3␟␞ a␟b␟␞ c␟d␟␞ ␝ Sheet4␟␞ e␟f␟␞ g␟h␟␞ ␝␜