[reggieband]

Our recollections of history of similar, however I also recall there being discussion about preventing semantic tags from being included in XHTML. A certain segment of the population believed it didn't belong in the document but rather as a corollary document in RDF or whatever (an argument of data normalization vs. denormalization).

Atom/RSS was involved in the debate because they were also trying to solve the metadata issue. Things like "author", "publish date", etc. are just as relevant to aggregation/syndication formats as it is to the document itself. Again, I'm summoning my fallible memory here, but one argument was if the metadata is relevant to both documents then it ought to be stored separately and linked to the HTML/RSS docs using a URL.

XHTML was involved because as an XML format it was conceivable to store your metadata separately AND to use XSLT to transform it into your XHTML/RSS/Atom document on demand. So RDF, Atom, RSS and XHTML authors all wanted a say on a metadata format that would suit all of those use cases. That is a tall order.

My personal feeling about the death of XHTML was it wasn't one big thing that killed it. It was hundreds of smaller disputes like this one.