This is exactly what I thought when I read the article. However, one needs to remember the reasons for the pushback that XML and XHTML got in the web developer

This is exactly what I thought when I read the article. However, one needs to remember the reasons for the pushback that XML and XHTML got in the web developer/designer community: The SGML based HTML allows all these nice quirks through the SGML declaration and DTD. There it is defined that tags are case insensitive, BR is always empty, you don't need to close TD and P etc... XML on the other hand has this stric notion of well-formedness where you can parse any well-formed document without a DTD or schema. This is what allows you to more easily invent your own tags and attach a style to them. Thus, with sticking with an SGML based language, HTML made a decision to make the authoring of the core language more convenient while sacrificing some of the benefits that XML would have had. It's a design decision and it has been debated a lot already. It's just something people should keep in mind.