I read it the same way. C++ is notoriously overstuffed with features.

I would imagine that Carmack specifically means that you can do unhelpful things, like dereference null pointers, access uninitialised memory, accidentally invoke undefined behaviour, etc. A foundational goal of Rust is to make those things nigh-on impossible.

And through those restrictions, like only allowing Send types to be passed between threads, you can even gain features over more permissive languages, i.e. datarace free code.

From " people don’t look to other languages because you can’t do something in c++, but more often because you can."

For me it comes across that you can do in rust what you can do in c++.

As for any reasoning for the change, be it learn-play, a more sane way of doing things, flavour of the month, or something else entirely.

I had a look for a rust vs C++, having limited exposure of the later and none of the former, and found this comparison insightful https://www.apriorit.com/dev-blog/520-rust-vs-c-comparison

But you may be right, if your referring to some unsavory aspects of c++ that rust may well avoid or obfuscate away from the coders train of thoughts.