The narrative recounts the journey of how Facebook transitioned from using Git to Mercurial as their version control system, driven by performance challenges and a lack of cooperation from Git maintainers regarding scaling solutions. The Facebook engineering team, facing slow Git operations due to their massive codebase, explored alternatives and found Mercurial's architecture more amenable to extensions and large monorepos, coupled with a welcoming community of maintainers. After attending a Mercurial hackathon, they were convinced of its potential and meticulously planned a company-wide transition, ensuring engineer buy-in through transparent communication and mapping of workflows between Git and Mercurial. This shift not only improved Facebook's internal processes but also contributed to the enhancement of Mercurial's performance, fostering a niche community of advocates for stacked diffs, which the author is now passionate about bringing to GitHub. The account underscores the human element in technical decision-making, emphasizing collaboration and communication over mere technical superiority.