I don't know why people are so often surprised about the number of employees in a company.
My company has half the number of employees, we're not remotely as relevant as SO.
It's basically a wiki with well under a terrabyte of data total and a billion requests a month (modest load in the grand scheme of web apps). It runs on less than 10 servers (https://www.datacenterdynamics.com/en/news/stack-overflow-st...). It's kind of bonkers to have hundreds of engineers supporting a handful of servers.
- Sales people, account managers, etc. for their ads business
- Sales people, account managers, etc. for their Teams product.
- Sales people, account managers, etc. for their Enterprise self-hosted product.
- Sales people, account managers, etc. for sponsored tags, collectives, etc.
- Support for the above (and the public Stack Exchange sites).
- Engineers for the above (and the public Stack Exchange sites).
- Community managers (who, among other things, fight abuse).
It all adds up. From what I remember most people working for SO weren't engineers, not even years ago (many were involved with the jobs site back then). There used to be a "Our Team" page which listed everyone who worked for SO, but it seems that's gone now.