C# is a pretty good language and for some tasks, probably a better choice. But D is very versatile, so once you get into it, you can expand your use into all kinds of different areas. It can do your regular application or line of business support code reasonably well, but it can then also expand out to new platforms, new paradigms, and tie together niches under one language.
As an individual programmer, it is pretty cool being able to write web apps and homebrew video games with the same language. For a company, you probably aren't going to be that varied, but it can still be good to dive into some special optimizations as needed.
Many of the organizations on this list use D for some combination of its flexibility. They have two areas of interest that need to co-exist and D lets that happen with minimal friction.
As an individual programmer, it is pretty cool being able to write web apps and homebrew video games with the same language. For a company, you probably aren't going to be that varied, but it can still be good to dive into some special optimizations as needed.
Many of the organizations on this list use D for some combination of its flexibility. They have two areas of interest that need to co-exist and D lets that happen with minimal friction.