I don't understand why this myth is still around.
C++ never had a killer app to start its momentum.
Neither did Javascript. Nor Java really (or maybe applets, back in the days?).
Languages can succeed on technical merits alone if they come out at the right time and fix real problems that programmers experience on current mainstream languages.
1. Extreme compatibility with the current entrenched language so you can incrementally migrate. C++ from C. CoffeeScript and TypeScript from JavaScript. Kotlin from Java.
2. A killer app (well, framework). Rails for Ruby. WinForms for C#. Applets and J2EE for Java (later Android).
3. A new platform where you must use the language to target it. C for UNIX. Objective-C for iOS. JavaScript for the browser.
There are a few exceptions here and there, but the above are the typical well-trod paths to success for a language.
What was Python's killer app?
What is Rust's killer app?
Go's?
Kotlin's?
Java is a counter example to your claim #3 since it not only does it run on all OS'es but you can also develop it on all OS'es.
Not a killer app, but the fact you have so many ML frameworks
> What is Rust's killer app?
That's clearly Servo.
> Go?
It was docker which really made Go take off, it was their first big platform.
> Kotlin's?
Android compatibility, before that it was a niche language not being picked up much.
C++ was immediately adopted by all major C compiler vendors as it came from AT&T as well.
Microsoft C/C++ 7.0 for MS-DOS was the very last one to adopt C++ on the toolchain.
It was the lingua franca of all major desktop OS GUI frameworks, leaving C just for their lower layers, MS-DOS (Turbo Vision), OS/2 (C/Set++), Windows (OWL, VCL, MFC), Mac OS (PowerPlant, MacApp), BeOS, Symbian.
If you were doing plain C GUI programming you were doing it wrong.
> Neither did Javascript.
JavaScript owns the browser, there is hardly any other alternative regarding "browser systems programming".
> or Java really (or maybe applets, back in the days?).
Java's portability was a gift compared with C compilers still in the middle of migrating from K&R C to ANSI C, C++ compilers which were silos with their GUI frameworks and a standard still a couple of years away to be fully defined.
More than today?
https://de.indeed.com/viewjob?jk=6c49a2deeb389df8&q=rust&tk=...
https://de.indeed.com/viewjob?jk=6823f26122417b2d&q=rust&tk=...