What isn't explicitly mentioned in the article but worth calling out here is AWS and other cloud computing environments. That is a major part of what enabled:

"Instagram had 13 employees when it was acquired for $1 billion by Facebook in 2012"

and

"WhatsApp had more than 450 million users world-wide when Facebook bought the messaging service for $19 billion in 2014, turning founder Jan Koum into a billionaire several times over. At the time of the acquisition, WhatsApp had 55 employees."

With prior tech booms, even if the computers that powered them were manufactured outside the US, they had to be installed and maintained in the US by employees of the company. Now all of that outsourced to Amazon and Google, who in turn have datacenters that employ few people.

Don't get me wrong- I love these services but a massive question still remains: Who is now responsible for job creation in the United States? It previously came naturally as a result of economic growth but that no longer holds.