Microsoft's Scalar will help you with a medium-large repo in pure history and file and file count size, but it won't help you with a repo with a very high merge rate. Microsoft doesn't actually have a massive monorepo anywhere near Google or Meta's size so they never came close to hitting the same problems.

Microsoft did, but that doesn't change the limitations imposed by git's design. Their repos just weren't as large.

> under 1 commit per second

Sure, for arbitrary pushes, that's not a big deal. But for large repositories, with those changes landing on trunk at that rate, once you start talking about "commits per second" it gets very difficult.