spamspan.js and anchortext

I would like to know what this code is good for which is found in spamspan.js file:

      // Replace each <spam class="t"></spam> with .
      if ($('span.t', this).length) {
        $('span.t', this).replaceWith('.');
      }

I can see it does replace the spamSpanAnchorTextClass with a ".", but currently I do not see why this is done.

In a custom module I am putting some email adresses in the spam span format like this

<span class="spamspan">
<span class="u">user</span>
@
<span class="d">domain</span>
(<span class="t">Anchor Text</span>)
</span>

But because of the code from spamspan.js shown above the anchortext is stripped out and instead the anchortext defaults to the email address.

Is this intended? If so, could someone explain why?

I took the code out of spamspan.js and then the anchortext is used as expected.