How is OOC more powerful than C? If it was more powerful, would it not be used in commercial applications? Would there not be OS's written in it (fairly popular OS's, on scale of Linux, MacOS, BSD's, Windows)?

I'm not a powdertoy dev, but it seems as though they don't know OOC, and I don't really see any reason they should have to learn it, if what they know works very well for the job.

"Use the right tool for the job" and I fail to see how OOC is any more "right" than C or C++.

Unfortunately? What makes it fast is the proper use of the languages! In the kernel they use assembly when they know they can spend more time writing this small bit than optimizing other C code, when apps come it's C or C++, when user interface material comes it's c# or python. Best of all the Linux kernel uses some custom C extensions that only GCC supports, They didn't think about changing C before picking another less common language I can guarantee that :p. Bottom line is that in projects other than just Linux you'll find it's either C or C++ not because everyone else is doing it but because it has the most support, SDK's, libraries, ease of use, and speed vs. development trade-off.

There is never any reason to use as odd a language as OOC unless you are doing something equally as odd but even then you need to look if it is the best for it, there are many OO adaptions for C after all (and many adaptions of C++ too) which can make the language easier to read or have more features or a combination but for something that has mostly been coded in an already low level language you don't need to try to switch to a different language unless you want to program it in something faster (ASM if you're crazy) or something higher level (which, other than legibility which is always a personal preference, there is no reason OOC is better than C++ to port c from)