The more the designers post about 3rd edition, the more I suspect that they are either deliberately obtuse or they didn't understand the game as it is actually played outside Renton at all. "Two EL 12s is only an EL 14." Well no kidding. And if your party is 12th level, it goes from being a cakewalk to being a moderately challenging fight. If your party is 10th level, it goes from a challenging fight to a climactic fight where there's a decent possibility a character or two might die. If your party is 8th level, it goes from a climactic fight to a stong possibility of a TPK--all depending upon the monsters and characters in question of course, but without assuming unusual conditions, that's the way it works. And it's exactly the way that the 3rd ediiton DMG said it works.
The only way I can see his comments making any sense at all is if:
1. His default 3rd edition encounter was actually EL=party level
2. His default 4th edition encounter is a challenging encounter
Now both of those make sense within the context of everything else I've heard about 4th edition, but that concept of 3rd edition doesn't resemble any adventure I've read, played, written, or run whether published by WotC or anyone else. Granted, a large portion of my experience is in Living Greyhawk format where the xp system writers have to use strongly encourages either a level+1/level +2/level +3 or level +2/level +2/level +2 three encounter module, but I've also played or run all of the fantastic locations products except for City of Peril, Red Hand of Doom, Expedition to the Demonweb Pits, Age of Worms up to the Alhaster mod, and Return to the Temple of Elemental Evil up to the crater ridge mines section and those all seemed to fit the default encounter level being party level+1 or party level +2 scenario. (The only published mod I've run that would fit the "most encounters at party level" formula is the new Dungeon Lost Caverns of Tsjocanth and I reduced the party's starting level from 11th to 9th for the mod and amped up the encounters in the first section (though I ran the second section more or less by the book) in order to make it interesting for my players).
[As an aside, I've actually found the CR/EL system to be a pretty good tool for estimating the difficulty of a fight as long as I don't go looking for ways to break it. Some monsters are simply mis CRed (arrow demons come to mind). Other monsters have powers that make them scale in very wonky manners (hezrou are the prime example of this--their blasphemy ability makes them completely unsuitable as a challenging encounter for lower level opponents or a part of a challenging encounter for equal level opponents, but once the players level exceeds the blasphemy caster level, they work fine). But as long as I keep away from the corner cases, it works quite well].