When design a language for everything nobody will use it for anything. When you design a language to simply accomplish one thing people will use it for everything. This is because people get the most efficient training using that simple language for one thing. From there it is only marginally more effort to carry some boilerplate.

That "one thing" could be real or propaganda. Rust's one thing is writing "memory-safe" without GC. Eventually the marginal cost becomes too high or your are tricked by advertising and "graduate" from awk to perl. From there depending on the pull of the community or the actual utility of the language you will use it for more and more tasks. If the community pull is strong your programs start to look like line noise or boilerplate hell. If the utility for your problems is genuine they remain simple but you probably aren't producing the most efficient binaries.

As for why c programmers don't just use -betterc well some do, but for most people the reality is that can just do it in c and prefer c -> c++ (ofc the vast majority of projects just start as c++ which makes -betterC )

c++'s one thing c with objects.

If you learned to code writing Go what did you do?

If you learned to code writing D what did you do?

That's not to say you can't learn to code from writing D just that it discipline, most people don't even know a problem exists before they are already learning some language or tool, nor do they have the goal of building everything, most programmers are lazy they want to build the minimal amount and end up building everything by accident.

Why don't experienced devs use D then? They think if they strive for ideological purity that they won't "build everything" next time, or they just enjoy ideological purity as it's own mental exercises. Unix faithfuls want to show that computing can be (conceptually) simple in implementation and use. Rust programmers want to show that those simple (to use) unix programs can be (memory) safe. To a senior engineer D is just too good and easy to take.