First of all there is no rule written that, the Linux users should use the Linux commands and system calls. Noway...
My friend's grand mother is using Ubuntu and of-course she is also a Linux user.
As Developer, you are not left to use Linux alone. Whatever you are doing in Linux as a Developer, all are possible with other paid OS [Hope you guessed :-) ] .
If you google it, you can find easily why c++ came . The Kernel is written in C, it can be even in asm, but very difficult to upgrade/change a single thing.
I strongly agree with whatever Marc Deop told.
Basically, its not like [ c > c++ } | [c++ > c ]. Its purely based on, what is objective of that final code output, where they going to deploy and who is going to use.