Consider:

 $ mkdir ./-e
 $ cat >./-e/test
#!/usr/bin/perl -w
die "It ran!";
__END__
 $ chmod a+x ./-e/test
 $ ./-e/test
It ran! at ./-e/test line 2.
 $ -e/test
Search pattern not terminated at -e line 1.
 $
[download]

So the practice does prevent one problem. Not one you are likely to run into, but a problem still.

For that last command, perl gets executed with a command line that looks like:

    perl -w -e/test
[download]

(at least on some operating system / shell combinations) and it doesn't know that "-e/test" is the name of a script file instead of the "-e" option asking it to interpret the code "/test" (which causes it to complain about not finding the terminating "/" for that pattern match).

I could envision some operating systems filling in the "--" for you such that including your own "--" would cause perl to report:

Can't open perl script "--": No such file or directory
[download]

though. So I'm not sure what to advocate at this point.

                - tye