Your examples are honestly terrible. C++ is a fast language, and it’s not easy to write fast x86 Assembly, especially faster than what the C++ compiler would spit out by itself. C++ doesn’t cause a slowdown by itself.

20 years ago people could code in Python and JavaScript, or about any high-level language popular today. Most programming languages are fairly old and some were definitely use for game development in the past (like C++), and game engines definitely date back way before 2003, or 1999 when RollerCoaster Tycoon was released.

RCT is an anomaly, not the rule. People who didn’t need to wouldn’t program in Assembly, unless they were crazy and wanted a challenge. You missed the mark by about a decade or so, even then we’re talking about consoles with extremely limited resources like the NES and not PC games like DOOM (1993), which was written in C.