I think the biggest issue is that back around 2011/2012 ish, when Facebook devs went to git core devs and asked how they could get git to scale to the size of t

I think the biggest issue is that back around 2011/2012 ish, when Facebook devs went to git core devs and asked how they could get git to scale to the size of their predicted monorepo, the response was roughly "no, shard it". git falls over and dies really, really badly when the repo gets stupidly large. There's an article alluding to the discussion here: https://engineering.fb.com/2014/01/07/core-data/scaling-mercurial-at-facebook/ https://engineering.fb.com/2014/01/07/core-data/scaling-merc..., but I can't find the original thread on the git mailing list.