Nobody was thinking anything. A bunch of managers of a group of frenemy corporations was condemned by the governement to share date. Every company sent the data to a trusted third party. This party removed the source company, anonymangled things a bit, taped them all together, and sent the result back to everyone. Managers wanted CSV as it was easy to open in excel, and they were going to let their underlings process them manually. Then it turned out to be a few 10s of millions of records and excel couldn't yet deal with >64k rows, so IT got to deal with it.