I mean, the obvious answer is that it's an extremely stupid idea that by all accounts fails at its one special trick and fundamentally can't operate without making a mess. Even the absolute best possible spherical cow outcome will still leave a bunch of gunk stuck between your teeth, but the most likely occurrence is that it just won't do anything at all most of the time. Consumer Reports called it messy, ineffective, and insignificant.

If you want a water flosser, just get a water flosser. Don't rely on microchip-AI-based optical targeting of microsprays from a lilliputian fluid reservoir inside a mouth filled with toothpaste and saliva to tell you where your teeth are.

Oh, you meant why they're leaking and dying. Right, right.