I don't find it particularly surprising. D uses a garbage collector while C, C++ and Rust do not. D's GC can be disabled but that isn't that useful when most D code including the standard library until just a few years ago were not written with that in mind.
D is much more closely a competitor of C# than it is C++. D has a few nice features like advanced compile time programming but the actual nuts and bolts that Staff engineering management looks isn't really solid. D's GC is a design straight out of the 80's. Dmd has good compiler throughout but code quality isn't very good. Ldc is much better but compile times are much longer.
Adopting languages at FAANG beyond a single team just yolo deploying them to production requires integrating dozens of engineering systems for everything from post mortem debugging to live profiling to authentication systems. The cost to do this is in the order of tens of millions of dollars.
D just isn't suitable as a C or C++ replacement in the places that actually require it and the cost to enable it in large companies isn't worth it for the incremental improvement it does offer in some areas.
D is much more closely a competitor of C# than it is C++. D has a few nice features like advanced compile time programming but the actual nuts and bolts that Staff engineering management looks isn't really solid. D's GC is a design straight out of the 80's. Dmd has good compiler throughout but code quality isn't very good. Ldc is much better but compile times are much longer.
Adopting languages at FAANG beyond a single team just yolo deploying them to production requires integrating dozens of engineering systems for everything from post mortem debugging to live profiling to authentication systems. The cost to do this is in the order of tens of millions of dollars.
D just isn't suitable as a C or C++ replacement in the places that actually require it and the cost to enable it in large companies isn't worth it for the incremental improvement it does offer in some areas.