Then you're doing federated development, and you should continue to use Git or another tool that supports that style of development as a first-class activity.
Many years ago, I read that > 90% of all software development is in-house private stuff. (Billing systems, custom workflow management software, etc.) A big chunk of the rest is software for sale by a company. If you have federated development going on within the bounds of a single company, you've probably also got organizational silos, which is a problem.
I suspect open source and SAAS have shifted that statistic in recent years, but I'd bet most software is still developed by a group of developers who all at least know each others' names, and can at least email each other, if not buttonhole each other at the water cooler.
Other shifts in the market, such as from boxed software on retail shelves to app stores is a net zero in this discussion, since the software is still developed the same way.
> It seems to come down to...centralized vs federated
Yes. The popularity of Git has associated "DVCS" with federated development, but one of the points I'm trying to make is that you don't have to give up on the benefits of a centralized repository if you need a DVCS.