https://dlang.org/blog/2017/07/28/project-highlight-funkwerk...
Companies using Java or C++ don't switch because a language is "sufficiently different". I've been involved in programming language discussions for decades and I've never heard of a company switching to a language because it was different from what they were already using, though being too different is a common reason for not switching.
{For those not aware, D has intentionally kept compatibility with C as a priority, to the point that you can set a compiler flag and restrict yourself to "betterC". You can translate C code to D without making many changes to it.}
When switching is costly, the potential upside must be big. When the other language seems similar, the upside also seems limited. When there are few differences, you can rationalize staying with the old language, because it may catch up with the features, or you can emulate the missing features, or just live without them, if the differences are small.
[1] A random commenter on HN might well conclude that there's no benefit to D's templates without using them.