Lemmy is written in Rust and even high experienced and capable C++ developers do not know how to work with it, plus the language itself is not finished.

that’s just plain false. It’s easier to use Rust than C++ because most of the pitfalls are eliminated, and many tools helping to get things done are built in nd have good quality. C++ devs just have a hard time getting used to the differences. It’s also questionable whether rust is unfinished. It’s not like its “beta” or “pre-release”, and if your point is that it’s still getting new features, then consider that C++ and Python does too.

python is better for prototyping, and it can be better for tools and simpler software. but if you think Python is better for “production” generally, then look at Matrix Synapse.

that being said, I agree that Rust is more complicated than other languages, but not by a large margin. but yeah, it matters for beginner friendliness, and I would never recommend Rust for someone who is just a beginner in programming; but neither would I recommend C or C++ for them.
though to be honest, I would be happier if the defacto beginner friendly language would be something with stricter types.