You can absolutely make a complete, featureful program in Rust without naming a single lifetime, or even without dealing with a single reference/borrow.

But Rust is a dramatically smaller language than C++. The various subsets of C++ people usually carve out tend to be focused on particular styles of programming, like “no exceptions” or “no RTTI”. Notably never things like “signed integer overflow is now defined”, or “std::launder() is now unnecessary”.

This seems like a very strange position, code written for Rust in 2015 still works, and in 2015 Rust just doesn't have const generics†, or async, or I/O safety, so... how is that not a subset of the language at it stands today ?

† As you're apparently a C++ programmer you would call these "Non-type template parameters"