Yes. So? Does that mean that the programs written for them are written in C/Cpp too?

No, but presuming that the best language was used to implement these runtimes, these languages would be worse off it it weren't for C/C++. And the runtimes qualify as important software in their own right, simply because they inherit from the importance of all the software that runs on them written in other languages.

> these languages would be worse off it it weren't for C/C++.

Definitely.

> And the runtimes qualify as important software in their own right, simply because they inherit from the importance of all the software that runs on them written in other languages.

Also agreed.

The only thing I'm trying to disprove is the thesis that "basically" no important software is written in languages other than C/Cpp.

"thesis that "basically" no important software is written in languages other than C/Cpp", yeah, not one person in this thread said that.

> Do they not know that basically every important piece of software today is still written in those languages [C and Cpp]?

To add to what codex said, it's impossible to get really proficient at either Python, Ruby, or any other interpreted language without having some sort of understanding of the underlying platform.