I could almost be sympathetic to them not wanting to build a migration tool.
But the least they could have done is set up a way to permanently forward to another gmail account so at least old email addresses do not break. They did not do that.
Ooh, and one more super fun fact: there is no way to transfer ownership of a Google Drive folder to an account outside of your domain. Which is awesome when you're the owner of a large shared folder that needs to persist.