But in spite of any potential downsides, such a culture surrounding a tag set is essential to the effectiveness of the tag set, possibly more important than the shared elements, schemas, or “semantics”.

And there is shared culture in the XML space. Self-taught XMLers have a very difficult time making good XML; designing what a friend of mine calls “colloquial XML applications”. Reading specifications is enough to enable the creation of legal, and probably functional, markup applications, and might enable a genius to create something fresh, brilliant, and better than anything we are doing now. Most of us are not geniuses, most of us are at best capable with occasional moments in which we shine. And most of us benefit greatly from participating in the culture of the communities in which we work.