Why Facebook does not use Git – and why most other devs do • DEVCLASS - eviltoast
Facebook internal development started out on Subversion with a Git mirror but switched to Mercurial for source code […]
  • Facebook does not use Git due to scale issues with their large monorepo, instead opting for Mercurial.
  • Mercurial may be a better option for large monorepos, but Git has made improvements to support them better.
  • Despite some drawbacks, Git usage remains dominant with 93.87% share, due to familiarity, additional tools, and industry trends.