Consider the fact that in older dialects of perl (Perl 4 and such) that the parser can generally guess when something is supposed to be a filehandle and when it's not. (First argument of open, first argument to flock, close, etc...).

(Remember too that functions used to have mandatory ()'s and &'s! So the barewords weren't so ambiguous then...)

It only begins to get tricky and nasty when you have indirect filehandles and use <> for globbing.