Might be... I do not know much about older readers. From what I read there is mainly problem with M9x, precedesors of M92.
It seems to me that maybe some hardware invoked issues are not solvable at all or at very high cost.
Again. It may happen, that what seemed like good idea turned out as failure. I already named Fuze+. It has touchpad. It seemed to me as great idea, nothing may break, no switches.... In real life it was total failure with SanDisk's firmware and is so, so with RockBox firmware.
Another story of design failure by big company is GPS in tablet Asus Eee Pad Transformer Prime. It simply didn't work. Asus first tried to make it work by updating firmware, it did not work. Then decided to remove GPS from specifications. Users were angry and Asus finaly decided to deliver for free something you plug in tablet what made GPS work. It is not ideal solution because of many reasons, but at least something....
I do not know, who is responsible for not maintaining M9x firmware. It depends on agreement between distributors and Onyx. It might be that distributors should pay Onyx for firmware update and distributors do not want to pay...
What is the conclusion. One has to be carefull what he buys, no matter who is the producer. It is potentialy risky to buy an unmature product. It may become mature by firmware updates or not. There is no guarantie despite the size and goodwill of the producer.
I am one of the first users of M92. I bough it only based on experince of one user and bunch of videos he made. For me M92 was OK out of box. I am happy it is becoming better and better. It is (slowly) evolving into a really good tool.