But D&D, Koi, even Grimm are mere minnows in the industry. Focal, kef, b&w et al could buy these guys many times over for their IP. It happens in most other industries.
What IP? Cardioid speakers have been around for ever and there is little to no mainstream demand. They have some advantages and some disadvantages. If demand grows for some reason then the larger manufacturers will supply them. They are easy enough to design and manufacture as demonstrated by speaker DIY projects (indeed the D&D was a DIY project on diyaudio for a while before going commercial). At present the low level of demand seems to be satisfied by a few small manufacturers. Since a cardioid design is more expensive, more complex, larger and less efficient in a musically energetic frequency range there needs to be some pretty compelling advantages if it is to appear in anything other than a few expensive speakers.