Is it necessary to remove existing sorts?

In views_fb_like_plugin_display.inc the view sort is overwritten:

<?php
   // Remove the existing sorts, and add on ours.
    $this->view->query->orderby = array();
    $this->view->query->add_orderby('views_fb_like', 'last_updated', 'ASC');
    $this->node_nid_alias = $this->view->query->add_field('node', 'nid');
?>

Could you please explain why this is necessary? I'm trying to update the data for my most liked nodes and I had to comment this out to be able to process my top list. Many thanks.