Hahahahaha, no, I'm pretty sure I disagree. Let me break it down.
First, if you base your design on encounters, this means your encounters must be balanced. This creates the problem we saw in 4e of "microbalance," of ruling out elements of the game such as flight, instant death attacks, teleportation, etc., because such things are not balanced for the encounter. They let you bypass the encounter or dominate the encounter. They are, at the encounter level, wildly unbalanced.
Yet, for D&D, for many folks, they are essential. It is true that they are not essential for everyone, but it is NOT true that they are optional if what you're looking for is the "Core D&D Experience." That experience includes instant death, and it includes flight, and it includes teleportation.
It is also true that "microbalance" works in the opposite direction, it elevates things that were never designed to be encounter challenges into encounter challenges, in order to balance them for the encounter. This leads to the elevation of things like Rust Monsters and Nymphs and Dryads and Gelatinous Cubes into needlessly complex and dangerous creatures, capable of enduring an entire combat, and focused on the five rounds in which they will be alive before being killed, and reconcepted as combat-centric creatures.
Yet, for D&D, for many folks, these creatures are not necessarily there to be fought, or at least not to be fought in anything like a "balanced encounter."
So for those reasons to begin with, encounter-based design fails to create the play experience I want at the table, and it fails to create the quintessential D&D play experience that is identified with the brand.
That's a tremendously problematic way to form a brand.
Still, it is possible within the context of a broader based design to have well-balanced encounters, if you'd like. Only, it doesn't mandate them as a core game design principle. It allows for more variety and more options and an experience closer to the binary logic of myths and legends and less like a series of minis skirmishes.
That variety is worth holding onto. And the fact that it doesn't necessarily take away good encounter design is why you probably don't need to worry about it making everything suck all of a sudden.
You've played the 5e playtest, yes? What happens?