CUDA was just plain better back in the day, more feature robust, and more features in general. Much simpler to pick up as well, especially at the time with what

CUDA was just plain better back in the day, more feature robust, and more features in general. Much simpler to pick up as well, especially at the time with what tools and libraries we were forced to use NVIDIA also partnered up very quickly with many big players in the game, the sales people went to work, but they had the technological feats to back it up. After that, it's the network effect.