DSP of audio is still in its infancy. So many coders and gear manufactures have tried the plugin market and failed horribly. Very few people have even figured out very basic things like how to program a working fast attack compressor like that which has existed since the 50s. Now a truly hard knee compressor like most VCA ones? It doesn’t really exist in digital considering the control signal sidechain needs a working rectifier (no frickin way in older dsp) and threshold detector, which is basically a clipper. To anti-alias a hard clipper needs infinite bandwidth. Meanwhile analog compressors have had microsecond attack rates since the Fairchilds in the 50s. Considering DACs are barely improving despite better ICs, very few people know how to make an excellent dac. 10-15 year old units are still up near the top of the heap.