Easy: CSVs are human readable and writeable and humans tend to have a comma sign on their keyboard, while they don't have the ASCII record seperator visible (teaching them to use eg Alt + 30 will not work).
And if they had that key on their keyboard then you'd have the comma problems all over again: What if a ASCII record seperator shows up in the field?
And if they had that key on their keyboard then you'd have the comma problems all over again: What if a ASCII record seperator shows up in the field?