I think the article is not up-to-date because update server is working properly with template.
Here's the code I use in the templateDetails.xml
<updateservers>
<server type="extension" name="mytemplate" priority="1">http://www.domain.com/updates/template.xml</server>
</updateservers>
And this is the content of my http://www.domain.com/updates/template.xml
<updates>
<update>
<name>My Template</name>
<description>My Template</description>
<element>mytemplate</element>
<type>template</type>
<version>1.2</version>
<infourl title="My template 1.2"><![CDATA[ My template update ]]></infourl>
<downloads>
<downloadurl type="full" format="zip">http://www.domain.com/updates/template.xml</downloadurl>
</downloads>
<maintainer>Me</maintainer>
<maintainerurl>http://www.domain.com</maintainerurl>
<targetplatform name="joomla" version="3.[12345]"/>
<client>0</client>
<client_id>0</client_id>
</update>
</updates>