My answer applied to the root of your question.
The obvious answer is all the top of the line models for each manufacturer are covered by proprietary and company confidential laws and agreements to protect the investment they made developing their product.
The lower end aids are no longer protected and become “open-source” products where anyone can now copy and make them. So they are retired or obsoleted for that reason and because the components are no longer manufactured. Re-engineering obsolete products is not worth the cost for them. China and other emerging countries do copy and re-engineer the products for pennies on the dollar. Quality does suffer as a result of that.
The other part of the answer that is implied but not asked that you have to consider is the hardware/software symbiotic relationship. You can have the most “powerful” chip or circuit on the market, if one cannot manage those resources with the software and make it easily available to the users and audi’s … It is useless.
The early versions of Phonak Spice software is a good example.
While I readily admit not being an expert with HA’s, I am an expert on hardware/software platforms and these issues parallel many industries.
Cliff’s Notes or Cole’s Notes answer:
One cannot look at one component to judge the efficacy of a product. One has to look at the big picture … hardware, software, training, tech support, audi competency, audi support.
Any focus on just one item is pure marketing bull poopie.