There is a good reason to process code in html comments
and that is that you sometimes put javascript or css
inside comments to hide the code from old browsers
and if you turn off adp parsing then things like
<SCRIPT TYPE="text/javascript" LANGUAGE="JavaScript">
<!--
<include src="javascript_include_foo">
// -->
</SCRIPT>
will not work right.
I find the <comment> tag to be the most palatable
solution (since I also think removing the code from what you
send to the client is a good practice).