Thriving Silicon Valley companies were among the first to embrace remote work during the pandemic, but they've struggled over how to recall their high-paid employees to the office.

The delta variant has scuttled the return to work plans for many large tech companies. According to The Associated Press, Microsoft has pushed back return to work dates until October, while Apple, Google, Facebook, Amazon are delaying returns until 2022.

Most work at tech companies revolves around digital and online projects, making many jobs tailor-made for remote employment. But many of Silicon Valley's largest firms have operated on the premise that open office work was the key to productivity and recruiting top talent.

Tech companies varied — and sometimes quickly reversed — attempts to justify free food and expensive real estate may establish a new employment model that could ripple across much of U.S. business.

It may involve much less office work than once expected, which in turn could challenge one of Silicon Valley's most cherished notions — that open offices and employee perks are necessary to spark innovation.