I was referring to the fact that the tr simply clobbers all Unicode characters, while Text::CleanFragment uses Text::Unidecode to try to turn them into ASCII:

use warnings;
use strict;
use utf8;
use Text::CleanFragment;

my $s = "Ｈｅｌｌｏ．ｔｘｔ";
print clean_fragment($s), "\n";  # prints "Hello.txt"
$s =~ tr/A-Za-z0-9._-//cd;
print "<$s>\n";  # prints "<>" !

(I've actually encountered filenames similar to the above in the wild)