Oops, should say "slap the 5 doctype on it last minute" (past edit limit)
the book that i am reading right now says the same thing about HTML5 , very very sad.
It stems from HTML 5's origins and how... toothless the W3C is overall.
HTML 5 as we know it did NOT originate inside the W3C -- some people who didn't quite grasp how to use HTML in the first place formed the "Web Hypertext Application Technology Working Group" -- whatWG, which by admission of some of it's former founders set about not making an authoritative specification, but instead documenting "how people were doing things" and making a specification that matched.
Which sounds all nice and rosy, but at the time (late 2003, early 2004) "how people were doing things" involved (much like today) sleazing out HTML 3.2, the proprietary crap that came into existence between 3.2 and 4, and slapping 4 tranny on it -- in other words the worst of 1997 coding practices... which is why to those of us who embraced HTML 4 Strict, grasp semantic markup, understand logical document structure and practice separation of presentation from content, HTML 5 looks like exactly that, the worst of 1997 coding practices. It undoes all the progress of STRICT because it seems it's creators never grasped the point of it.
The "documentative instead of authoritative" philosophy continues to this day with HTML 5. The "specification" (and I say that in the loosest sense of the word") is more interested in documenting things browser makers come up with we don't need, than in telling people how to build websites in a sane and rational manner. I think this stems from the fact that there's this noodle-doodle nonsense being parroted industry-wide that "rules make things harder" - SINCE WHEN?!? Clear well defined rules -- for structure, for a site building process, for what tags actually mean -- makes life EASIER as a good specification ends up being a "how to" guide to success.
Really all the 'structural' parts of HTML 5 -- SECTION, ARTICLE, NAV, FOOTER, ASIDE reek of being made by people who don't grasp the point of logical document structure, or how to use numbered headings and horizontal rules properly. The BEST you can say about them is they make data scrapers lives easier; but isn't data scraper just a polite term for "content thief"? No offense, but how often do you find people asking how to STOP people from stealing content? Sure, let's add tags to make stealing content EASIER.
The rest of HTML 5 gets even worse... in 4 STRICT a number of tags were dumped or rejected in favor of OBJECT to remove redundancies and prevent vendor lock-in. Technically OBJECT was supposed to replace APPLET and IMG (yes, IMG), and is why EMBED, BGSOUND, and a host of other proprietary tags and attributes were rejected for acceptance. Along comes the idiotic bull known as HTML 5, and not only is EMBED magically now acceptable -- they introduce two new redundant tags DESIGNED for vendor lock-in in the form of AUDIO and VIDEO. Instead of letting the market decide what to use for codecs and containers, browser makers get to cherry pick their favorite pet codecs and shove them down our throats, laughably igniting a new media format war akin to the late '90's QT vs. WMV vs. Realplayer idiocy... You'd almost think the companies that threw their weight behind the WHATWG lost those wars to someone who wasn't even considered to be in the race at the time.
If you take the time to understand 4 STRICT and how to use semantic markup, and the entire reason things were done the way they were in STRICT, pick up good and sensible document writing and coding practices, you will very quickly find that HTML 5 offers little if anything of value as a markup specification... There's MANIFEST for applications and... and... uhm... Well, there's MANIFEST.
Though really sadly, HTML 5 has become a sick buzzword thanks to people calling all the really cool stuff HTML 5, when it isn't. CSS3, the new scripting stuff, all of it has not one blasted thing to do with being a markup specification, no matter how many people slap all the actually useful stuff under HTML 5's name.
Most likely this has been done since if you remove the actual useful stuff that has NOTHING to do with writing markup, the Emperor is standing there bare for the world to see.
Really HTML 5 reminds me of that tale. The vast majority of people praising it either don't know enough about what a markup specification is to open their mouths on the subject, or are simply afraid to say "Hey, you know you're flashing your willy at everyone, right?"
-- edit -- Oh, BTW -- what book? Be nice to find SOMEONE in print being realistic about things.