I’m not sure computer programmers do use C over C++ because although the two languages are similar in that they share a lot of syntax, they are also very different. For example, C is commonly used for systems-level programming.
By that I mean writing code or programming software which works on a computer’s hardware, for example, writing software to develop a printer driver or disk defragmenter. C++ is typically used by computer game developers because it “allows more direct control over the hardware and graphical processes (something very important in video game design)”.