cox & ftp

I am just curious; why would cox block inbound 25 & 80,
but not ftp(21)?

Certainly ftp has the potential for hogging bandwidth,
not 25. I know 25 had some spam implications, but hell there
is software to govern folks that are out of hand there...but why
leave ftp open?

I have no need for an ftp server, but found this curious.

-mike