9 - It's more expensive, the market won't tolerate a price rise on disposable batteries, they cannot sustain a 8x average life of their product at current prices.

0 - "Our technology is really a miniaturization technique that allows us to build the sleeve..., but the key is we’ve been able to miniaturize the boost circuit to a point that no one else has been able to achieve"

10 - Patent protection would add to the per-unit cost

9 - draws too much current when not in use. Theres some icom radio battery holders that are "famously" active, you can run a portable mobile radio (think hand held police radio or ham radio) on 2 AA batteries but the upconverter runs 24x7 once the batteries are installed so in 6 months, even if never used, the batteries are dead and in a year they're leaking. Think of the remote control for a TV that dies annually no matter how much or little you use it, all the amphours went into standby losses, operation energy was a rounding error. You can't run an upconverter for free, although technology is improving etc etc. Of course lower losses imply higher impedances which generally result in higher static sensitivity.

10 - "everyone knows" overdrained batteries leak, cheaper ones worse than the expensive ones.

Or that. That's probably it.