RAR != PAR. You could apply PAR2s to any format, even (gasp) a single file.
We do. Our tools use it to help customers in India upload multi gigabyte movies to our storage in the US.
But nobody uses RAR without PAR2, and I was responding to the bewilderment at those using RAR.
May be time to check again:
http://www.quickpar.org.uk/AboutPAR2.htm