[Teknoman117]

A few things come to mind, but I wasn't even alive then so what do I know XD.

On one hand, it seems rather strange, because back in the early days of C (and later C++) there were far more CPU architectures in play. Every big Unix hardware vendor had their own CPU architecture, whereas today we only have about six. (In my mind: x86, arm, mips, risc-v, ppc, and s390x)

But it might be that in the early days of C/C++, development involved connecting to large shared Unix environments where the machine you developed on what always the machine (or at least the same type of machine) the program would run on, and also that those vendors weren't exactly incentivized to make developing for competitor's architectures easy.