To make an engine it's ok just to gather a bunch of programmers.

To make a game (even a tiny one) you need artists, sound designer, designers and so on and that's what makes it significantly harder

The Forth community takes this one step further: it's more common to see someone discussing their implementation of the Forth language, than to see someone discussing what they developed in Forth.

I'd bet that most new Forth implementations are done for CPU:s that already have vastly more powerful languages available. So if someone want to get stuff done they would probably rather use a more productive language for that. But if they want to tinker around I'd imagine a Forth implementation would be a pretty fun learning experience. I'm myself implementing a Lisp (MAL) just because it's fun. I'm not really planning on using the implementation for anything though.

Competent Forth developers consistently seem to consider Forth a far more productive language than C. Not something I can comment on personally though, I know C far better than I know Forth.

So they say. But every architecture known to man already has a Forth implementation. So why bother make another when you can get busy doing useful stuff? I would say it's just for the fun of programming a Forth.

Common lisp too

This is a pretty common joke about all game development, not just Rust.