To me it looked like one of the points of Git was that one could work on anything from the entire repository locally, i.e., for example, without having an internet connection, e.g. when on an airplane. (I think having one huge repository is the problem here.)
Well, Git was indeed created to serve Linux kernel development. So decentralized access for the people writing patches all over the world was useful. However, when companies started using source control for their monorepos which developers access through a work network or VPN decentralization takes a backseat to business concerns. Different use cases and all that.
I think the problem there, is that you then basically wind up with Git on the backend and an SVN-like layer over the front. Which seems a bit silly. SVN is a very robust project that works really well. Why not add git-like porcelain to SVN if you're gonna force devs to have an network connection so they don't have to download a giant git working directory.
Smart people are working on all this, so I'm sure there are reasons, but in the all the instances where I've had to interact with a monorepo, it was because the tech debt was too high to pay off to break it apart, not because it was better.
And if you're indebted to the point where you have no point in paying it off, you damn well better have leveraged assets against it (i.e. a cash cow of a business, like MS Word or Facebook)
That's interesting. I've never been an insider and it was several years ago, but Google spoke in pretty glowing terms of their monorepo when I heard them talk about it. That's neither here nor their though, not my personal preference either to be fair.
As far as Git's killer feature I think decentralization is only one part of it. Being able to deal with the change graph directly is sometimes handy. And knowing the basis of the model, I find Git pretty easy to understand even when history gets fuzzy. Not sure but I think Darcs might be even better for that, just without the mindshare.
