The new LED backlights allow the individual pixels to be 100% off, and now they can compete against plasmas. They also do not have the glare of a glass plasma if you have high ambient light, like a south facing room with no blackout blinds.
This is factually untrue.
1) LEDs don't allow pixels to be wholly turned off. LED TVs come in two ways:
a) edge-lit, meaning there's a ring of LEDs behind the screen. This is noticeable at almost all times
b) array-lit, meaning there's a grid lf LEDs behind the screen.
Unless the LEDs are the size of the pixel and isolated, each LED lights many (many!) pixels. So it's impossible to turn one off yet keep the one next to it on. Typically, this is called "haloing," because an attempt to light a star in a black sky will make the entire area around the star brighter. The LED would have to be the size of the pixel, directly behind that one pixel, and wholly isolated from the surrounding pixels, for what you said to hold true.
On a plasma, you can light individual pixels, so this is not a problem.
Simply put, plasmas are objectively better when it comes to black levels, so the quoted information is wrong. I'd say they're objectively better in picture quality, too, but I suppose picture quality isn't something you can be objectively better at. Still, when you look at TV reviews, plasmas are always on the top.
As for the screen glare, most LCD TVs, LED or other, use a glossy screen these days for the same reason monitors do - gives more vibrant colors and suckers more people into buying in stores. But it's true that many LCDs still come with the matte while no plasma will.
All of this is moot, though, with Panasonic discontinuing plasmas the best TVs on the market are, well, no longer on the market. LG and Samsung plasmas weren't as good, no surprise since Panasonic spent much more money on R&D and had purchased Pioneer's Kuro tech.