On Friday, another one bit the dust. As Snap's shares plunged following disappointing results, it became clear that the myth that a feisty young challenger to Facebook could topple the social media giant from its perch was just that - a myth.
Of course, the company behind Snapchat is still a very impressive young business, building an audience of 173 million mostly young daily users in just five years and changing the way they communicate, in fun and inventive ways.
But its future as an independent company looks uncertain, with talk of it being swallowed up by Google or another web giant.
The deep pockets of Facebook, which bought Instagram and WhatsApp, and has relentlessly copied any challenger it couldn't buy, meant that Snap was always going to struggle to deliver on the vision of rapid growth it outlined when marketing its shares earlier this year.
And that just adds to the growing sense that the days of creative destruction in the technology industry may be over, and that we are looking at a world where the big winners of the past decade - Google, Amazon, Facebook and Apple, or "Gafa" as this four-headed beast is sometimes described - will rule unchallenged.
In its young life, Facebook has constantly been seen as under threat - and indeed it has fostered that view whenever there has been talk of curbing its power.
Just as it had left Bebo, MySpace and Friends Reunited in the dust, the story went, it too could soon be heading for obsolescence as fickle users turned to the new, new thing.
But the truth is the social media war is over and Facebook is the winner.
A few smaller players such as LinkedIn and Twitter and, yes, Snapchat will have substantial audiences but struggle to make much money.
But, apart from in China, the company that is now worth nearly $500bn (£385bn) will continue to be the biggest force in the way we communicate for the foreseeable future.
The other members of the Gafa quadrumvirate also look secure in their dominance.
Google won the battle for search on the desktop long ago, and has now become equally powerful on the mobile internet.
Amazon is the undisputed champion of online retailing and logistics and has built a lead in cloud computing.
And while Apple has a relatively small share of the global smartphone market, it has gobbled up most of the industry's profits for the past seven years.
Now, key trends in technology mean the giants are poised to grow immeasurably richer.
As advertising spending is aimed increasingly at phones, Google and Facebook already have most of the mobile ad revenue.
But it is in the use of artificial intelligence that the technology giants aim to cement their technological lead.
I was told recently that an AI researcher emerging from a top US university can command a salary of $500,000 a year in a first job.
It is not start-ups paying that kind of money but Facebook and Amazon.
Of course. you can find lots of brilliant artificial intelligence researchers in the UK - but many of them now work for American companies, with start-ups such as DeepMind and Swiftkey snapped up by Google and Microsoft respectively.
So, should we worry about the huge and growing power of these businesses?
Unsurprisingly, the companies still insist that at any moment they could be disrupted out of existence by a smart new start-up.
But, so far, American competition regulators have also been pretty relaxed, because they tend to focus mainly on whether consumers are paying excessive prices because of a lack of competition.
With social media and search giants offering excellent services for nothing, they see few causes for concern right now.
In Europe, regulators tend to be somewhat more sceptical about whether companies with monopoly powers deliver for consumers in the long run.
That is why we have seen the EU take action against first Microsoft and now Google, where American regulators have mostly left them alone.
And while Europe's competition authorities insist that any action they take is based on law, not politics, there is undoubted concern among the continent's politicians about so much power over our lives being concentrated in the hands of a handful of companies based on America's West Coast.
So far, however, Facebook has been relatively untouched by this tougher regulatory approach, even if politicians complain about issues such as fake news and the presence of extremist content.
In the past year, we have seen it, arguably, play a key role in electing an American president, its global audience has risen above two billion, and it has now moved into video content, taking on YouTube and Netflix.
In an interview this weekend with the New York Times, the former Downing Street strategist turned Silicon Valley guru Steve Hilton said: "A lot of the foundational philosophical approaches of tech leaders are actually all about decentralisation of power."
Mark Zuckerberg may tell us that Facebook - where, incidentally, Mr Hilton's wife is now a senior executive - is all about giving power back to communities.
But increasingly it seems that wealth, influence and control of the key technology of our age, artificial intelligence, are being centralised at addresses in Menlo Park, Mountain View, Cupertino and Seattle.