Of course secrecy is not the sole reason he left. Swift was developed 100% in secrecy for the first 3 years of its life, and even after that, Chris was able to navigate the open-sourcing culture shifts required of Apple to make that a reality, no small feat.
Though boring and lazy, it's extremely popular for the hivemind to take aim at the throne. Note it's why any article critical of Apple (or every damn blogger's tbMBP/macOS -> Linux article) goes immediately to the HN frontpage, while interesting technical discussion re: Apple products or news showing they're still the market leader remains barely discussed.