The tech giants are too big. But so what? Hasn’t that always been the case?

As the men who run Silicon Valley will be the first to tell you, a company’s size doesn’t matter here. For every lumbering Goliath, there are always one or two smarter, faster Davids just now starting up in some fabled garage, getting ready to slay the giants when they least expect it.

So if you’re worried about the power of the Frightful Five — Amazon, Apple, Google, Facebook and Microsoft — just look at how IBM, Hewlett-Packard or monopoly-era Microsoft fell to earth. They were all victims of “creative destruction,” of an “innovator’s dilemma,” the theories that bolster Silicon Valley’s vision of itself as a roiling sea of pathbreaking upstarts, where the very thing that made you big also makes you vulnerable.

Well, maybe not this time.

The technology industry is now a playground for giants. Where 10 or 20 years ago we looked to start-ups as a font of future wonders, today the energy and momentum have shifted almost completely to the big guys. In addition to the many platforms they own already, one or more of the Five are on their way to owning artificial intelligence, voice assistants, virtual and augmented reality, robotics, home automation, and every other cool and crazy thing that will rule tomorrow.

Start-ups are still getting funding and still making breakthroughs. But their victory has never been likely (fewer than 1 percent of start-ups end up as $1 billion companies), and recently their chances of breakout success — and especially of knocking the giants off their perches — have diminished considerably.