It's not vendor locking when the functionality doesn't exist on the other platforms.
Just take as an example cuFFT. That's a core library that's been there pretty much since the beginning with CUDA. It has a compatibility interface compatible with FFTW, which everybody knows how to use. So porting from a CPU code that used FFTW was trivial.
rocFFT is not as mature, the documentation is poor, and the performance is worse. And that's where there is an equivalent library that exists. In other cases, there isn't one.
Just take as an example cuFFT. That's a core library that's been there pretty much since the beginning with CUDA. It has a compatibility interface compatible with FFTW, which everybody knows how to use. So porting from a CPU code that used FFTW was trivial.
rocFFT is not as mature, the documentation is poor, and the performance is worse. And that's where there is an equivalent library that exists. In other cases, there isn't one.