I ve had the same question. I think it's because over the years, companies and employees have gone virtual

-- Companies have gone virtual, they exist in slack, basecamp-type tools etc. In the 2000s it would sound unthinkable to put your corporate secrets in someone else's server. Today it's commonplace

-- Employees have gone virtual. Their CVs are in github, and the flaky silicon valley market has made them conscious of their personal image / website. They prefer a supermarket of opportunities rather than a long-term relationship

These things oiled up the gears for the transition, and covid gave it a big push.