- 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.
There’s also a whole industry of ex-Googlers reimplementing Google tooling as SaaS services to sell to other ex-Googlers at other companies.
There’s even a lookup table: https://github.com/jhuangtw/xg2xg
(some of those are open source projects, some are SaaS services)