I guess you mean SQL place holders under DBI - yes, there is a very good reason, quoting.

If you manually construct your SQL queries, you have to escape all nasty characters like spaces, commas (with quotes) and most disturbing and error prone, apostrophes (') and binary values. Placeholders alleviate you of that onus, so they are a good thing to use, even just for a one-shot script.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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