What’s often overlooked is that adoption of MMX was slooooow. Intel compiler were the only intrinsic data types for years. The big win was DirectX 3 audio drivers that used premade Intel libraries. It took at least five to ten years for SIMD to catch on, but the never stopped Intel from evolving it. Then they lost the GPU wars lol rip larabeee.
And now the legacy of Larrabee, AVX-512, is only properly available on AMD for consumers :D
MMX had heavy adoption in image and video processing. IDCT, motion prediction/compensation, YUV/RGB conversion, and alpha blending all benefited from it.