I don't know why, but the only reason I can think of
makes the site operator out to be really stupid/vicious.
Without a HEAD a client cannot determine the state of a
page and will have to refetch with GET. For users this
means you might be able to show more ad's. It might
also be possible to exploit this for search-engines as
well.
However according to this
page
it would seem that HTTP/0.9 did not have HEAD. Though
I hope there aren't *that* many HTTP/0.9 hosts out there...
--
perl -pe "s/\b;([st])/'\1/mg"