OpenMP has been around for a long time. People know how to use it, and it has gained many features that are useful for scientific computing.
The consortium behind OpenMP consists mostly of hardware companies and organizations doing scientific computing. Software companies are largely missing. That may contribute to the popularity of OpenMP, as the interests of scientific computing and software development are often different.
The consortium behind OpenMP consists mostly of hardware companies and organizations doing scientific computing. Software companies are largely missing. That may contribute to the popularity of OpenMP, as the interests of scientific computing and software development are often different.