but I tend to think of waka waka as STDIN

And that's exactly the kind of thinking I'm arguing against.

The empty angle-brackets have precisely one function: to be used to process the files specified on the command line to create a filter written in Perl. That it happens to read standard input if no filenames are specified or if a lone dash is included, is merely a special case, not the typical case. So, I'm working everywhere to kill the bad memes, and yours is an example of that.

-- Randal L. Schwartz, Perl hacker