Personally, it makes a lot of sense. Sure if there's no need to chomp a value then it shouldn't hurt. However the function *must* be assuming the input it to be modifyied in some way otherwise you'd not pass a value to it that you expect to be modified.

sub modify {
   chomp( $_[0] );
   # whatever else happens, you've just potentially modified $_[0]
}

modify('fred');
# What would you expect to happen to 'fred'?

my $f ="fred\n";
modify($f);
print $f;
#fred
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sub modify2 {
   # Create a copy of the input
   my $input = $_[0];
   chomp($input);
}

modify('fred');
# works now because we're not modifying the input, but a copy of it.

my $f ="fred\n";
modify($f);
print $f;
#fred\n
[download]