My guess is because many employers had contracts with them and if you're using it at work, it's likely your go-to for leisure at least if you don't know any better about other options.

It bothers me that people are willing to jump to use their company license of zoom for personal gatherings. I have no idea if it's possible but what if a license holding company, whose employees are utilizing their zoom account, can record any sessions in use by the account?

Even if it's not possible, I hate mixing my personal life with work, and when I see the opportunity I always bring up Jitsi as an option over Zoom.