I have no idea, and I didn’t mention CI one way or the other. I don’t even have a shred of evidence that my wag on your question is correct. But for-profit companies are motivated by very few things and they all boil down to money, the opportunity to make more or the risk of losing it. If HAs such as you describe were readily available but no longer are then it’s logical that either they were deemed not sufficiently profitable or posed some form of additional risk to profits.
Not sufficiently profitable could be just too little demand, but once developed and on the market that would seem less likely, the expensive part is done and they have epically high margins. But if they largely flopped and most people weren’t satisfied or they were unreliable, so auds stopped recommending them, then they are unprofitable and a risk to reputation. Again, just more pure wags on my part hoping to attract the attention of someone who actually knows something to come in and correct me.
Batteries have come up a couple times so maybe it’s as simple as that, too many dissatisfied customers because current batteries can’t cope with the levels (overall load at whatever mix of frequencies required). Fortunately there is an enormous amount of R&D on batteries these days for other reasons but as we’ve seen often enough there are risks when you try to pack too much power into certain types of rechargeables. You don’t want your HA catching fire in your ear, and for now anyway single-use batteries still pack more power per volume without those risks.
So take your pick, your guess is probably better than mine.