C++ is a language with perfect 30-year backwards compatibility, and which mostly-maintains compatibility with another language it forked from (C), after 40 years of diverging development.

Rust is a language which isn't backwards-compatible, and certainly not compatible with source code in other languages.

Now, sure, Rust has its advantages, but - how can you fault C++ in the context of compatibility?

this compatibility sucks sometimes.

for example you want to add nice feature to c++ with nice syntax, but there is a similar syntax somewhere in C that nobody uses, but you have to support it. you end up with nice feature with horrible syntax.