Coming from MTB, there might be parallels to the tinkering solution called "Shigura" which describes Shimano brake levers paired with Magura calipers. The problem is that the calipers need much more oil volume than the shimano ones (and compounding that, Magura has 2.0mm brake rotors compared Shimano's 1.8mm), so the reservoir in the levers is too small. So if you use a Shimano rotor and the brake pads (or/and disc) are worn, you are getting to the point that you can no longer build up pressure, because you run out of oil. The tinkerers running this combo normally are aware of this and often bleed the brake at like half-pad-wear (actually overfilling the brake - resetting it like this would pop the reservoir) to not run out of braking juice. So yes, too small a reservoir can lead to brake failure.
That said, I agree that both brakes failing at the same time is still strange. It might be that one brake stopped working properly, leading to the rider compensating and overusing the other one and actually boiling the liquid or destroying/glazing the pads. But that's pure speculation.
At any rate, any trustworthy company would launch a serious investigation after something like this happened. On the other hand, in days of social media and viral stories destroying companies/lives with little regard for truth, I can somewhat understand Magene's "official" reaction to not react in any way that could construed as an admission of guilt. If this happened with Shimano and Sram groupset, they wouldn't react with "Yeah, might be our fault". How long did it take Shimano to admit their cranks were falling apart? I would expect that internally, they are looking into this really carefully, but maybe I'm just naive. Time will tell.
I suspect they didn't actually fail at the same time. The rear likely failed first and the user didn't realize it as they likely used both levers when braking and the front brake is what you primarily feel and focus on modulating to avoid going over the handlebars.
The excuse Magene gave for not allowing Luke to show the video of the backing plates grabbing the rotor doesn't make a lot of sense. No judge is going to find Magene financially liable for a crash with pads worn down to the backing plates. Demonstrating a basic last ditch safety feature that exists on every other hydraulic braking system wouldn't change that, and would reassure us that if
we're negligent, their brakes will warn us and do what they can to bail us out.
Additionally, not publishing the fluid volume(and brake line length) in the system doesn't instill confidence. How bad was the brake bleed? I've done a subpar brake bleed before which resulted in a bit of a spongy shimano lever. Would that bleed have taken out my brakes on the QED groupset? If the measured volume of oil was egregiously low, nobody would worry, knowing they could follow the Park Tools tutorial reasonably well. If this piece of information were published, we could also replicate the issue ourselves and be sure of the cause.
As it stands, it's still possible that this user
1) Picked some lightweight rotors that the brakes should be able to handle
2) Picked some official magene resin brake pads
3) Wore down said pads to a reasonable level for a hydraulic brake system to be able to handle
4) Performed an imperfect but not egregious bleed job.
If that's possibly the cause for totally losing your brakes flying down a mountain, I'll stick to my Shimano brakes. I like my resin pads, and if my LBS leaves a few bubbles in my lines I don't want my brakes to go out the before I even wear off the pad material.
