A mix of misteps by D, and some unique advantages of rust. * Releasing D under a closed source license was a non-starter. This has killed every language that h

A mix of misteps by D, and some unique advantages of rust. * Releasing D under a closed source license was a non-starter. This has killed every language that has tried in the past 30 years. * Garbage collection was really the only memory management until recently. Manual memory management has always felt clunky and tacked on. Ownership and borrowing came really late to the game in comparison with rust. * Rust embraced all of the best parts of ML, like algebraic data types and pattern matching and strong static typing, but combined them in a package that made for extremely fast software with low resource utilization and static memory management. They combined it with hygienic fully typed macros. They added type classes, securing the majority of the benefits of OOP while still maintaining a functional style. Whereas Rust has taken influence from a broad range of PL research, functional programming concepts, high assurance concepts, etc., and applied them to system programming, D has always just felt like C++ with garbage collection. The one area where I think D still has an advantage over rust is GUI development. Functional programming advocates make lots of platitudes of functional reactive programming, and there are no shortage of toy examples for it, but when it comes down to industrial use, OOP still rules the roost. And while Rust gets most of the benefits of OOP, they still don't have anything approximating inheritance, which just works too well for GUI development to give up on. Maybe Rust will address that in the future, but it's not there at the moment.