If you buy a Mac you get the Apple developer toolkit which allows you to make apps for approximately 1% of the world's computing population. It's a minority, but one that cares and will love you for your efforts.
(the last part of that second sentence may be a lie)
Indeed, it appears that you are correct!
That's just bloody messed up!
<!doctype html> HEAD STUFF <body> BODY STUFF
The 'compiler' presumably being the browser? The same browsers that have been the bane of our lives for how many years because of inconsistent adherence to even vaguely consistent standards? And now that many developers have got around to properly formatted HTML code what do W3C and their friends do? Throw it out the window.
Hurrah for progress.
Well it's more a case of the browsers understood the HTML structure perfectly well, they just displayed it differently.
Most of the problems I have with IE are related to CSS anyway.