The reason is obvious: These three companies dominate the smartphone industry with a shocking totality.
Google dominates mobile search revenue in part because of its Android platform and in part because of its iOS apps. Google made about $5.2 billion in mobile ad revenue last year worldwide and grabbed an incredible 93.3% share of the U.S. mobile search ad market.
The rest of the industry is fed up with watching Apple, Samsung and Google run away with all the money. Now they're fighting back.
The industry is competing again and they're doing it right -- with innovation, imagination, design and sound strategy.
Here's how each of the leaders was challenged in Barcelona this week.
Apple didn't have a booth, yet had a presence at MWC not unlike Lord Voldemort's in the Harry Potter series -- the scary, powerful entity that must not be named.
A general mob scene at the HTC booth involved long lines forming behind the dozens of tethered demo units of the recently announced HTC One phone. Many people were snapping pictures of the HTC One with their iPhones.
The HTC One is by far the most beautifully designed Android phone I've ever seen, with its elegant, unibody aluminum construction.
The HTC One challenges the iPhone on Apple's own terms -- with elegant hardware design, a fantastic camera and a compelling user interface.
Apple's monopoly on elegant hardware design is officially over.
An even bigger threat to Apple's dominance, however, is the general excitement over phones totally unlike iPhones.
The hottest thing in smartphones at the show was raw power: 13-megapixel cameras, blistering-fast mobile processors, giant screens, incredibly loud and clear speaker systems and surprising and innovative connectivity options to TVs and other devices.
The iPhone suddenly feels stale and feeble.
Samsung had an enormous booth, as usual, but didn't announce its upcoming Galaxy S4 phone, which will be unveiled March 14 in New York.
Samsung's new handset competitors are hitting the company with a combination of great design, compelling features and raw power.
LG demonstrated some surprising technology that I didn't think was even possible. They showed an LG Optimus G running a graphically intensive game mirrored over HDMI and upscaled to Ultra HD TV (also known as 4K) -- a TV technology so new that they're selling for around $20,000 per TV set. Hollywood isn't even producing much 4K content.
ZTE surprised the MWC crowd by announcing a phone called the Grand Memo running Qualcomm's Snapdragon 800 processor with LTE connectivity -- which can run at a clock speed of 2.3 GHz. (Note that Samsung's upcoming most-powerful phone, the Galaxy S4, will reportedly run the slower Snapdragon 600 in one model for the U.S., and a second version running Samsung's eight-core Exynos 5 Octa chip for the European market.)
In the wake of MWC, Samsung's design, performance and feature advantages on the high end of the market are seriously eroded.
But there's trouble on the low end, too.
For example, Nokia's Lumia 520 phone is a pretty advanced Windows Phone smartphone that should cost less than $185. Upstarts like Huawei and ZTE were showing low-end phones that provide most of the features and functions of high-end phones, but at very low prices.
These are the kinds of phones that are likely to chip away aggressively at Samsung's global market share.
Google decision to go boothless at MWC this year surprised attendees. Last year's Google booth was ginormous and their show presence overwhelming.
Google's Android platform is by far the world's biggest phone operating system. Devices running Android were everywhere at the show.
But there's trouble in paradise, and this was plain to see at MWC. The problem: The marginalization and commoditization of mobile operating systems in general and Android in particular.