New hires share their personal handle because that is the only handle they have; i.e., they have not played games on their company-provided accounts yet.
You don't need to share your primary account, you can theoretically apply for the job with a secondary, or none.
This isn't exactly strict separation of personal life, you are basically working at a specific venue and playing at that same venue just without your uniform; people know and you won't last long in similar situations elsewhere either (unless you're maliken/s2 games)
