Freelancing began to gain momentum after the global financial crisis of 2008. Then a lot of people were out of work and began to look for a remote job. Plus, companies began to cut jobs in offices and send workers to work at home. This marked the beginning of the movement of freelancers.
You're right. I am personally acquainted with several people who became freelancing after their employers offered to start working not at the office, but at home. I think that there are many such stories.