Interesting but I'm not sure comparing the toy batteries and boat batteries would be apples to apples.
Are you aware that a Li-Ion "boat battery" is actually a case built to be similar to a traditional boat battery, but with lithium-ion cells inside? Think of it like a "box" that the Li-Ion cells have been encased in for standardization. The root level issues appear to be with with the construction of Li-Ion cell technology, not just isolated applications - their apparent fragile nature, temperature sensitivity, etc. I'm not sure a hooverboard is a "toy" in the sense of typical toy power profiles. They have a DC drive motor that requires a good bit of power. Sound familiar? Boeing had issues with them in the 777 (fires); that's not toy stuff either.
As I said, each owner is free to decide what to use. But, no engineer I've spoken with who owns a boat would be willing to use them even at parity pricing with conventional technology due to the uncertainties involved - I'm one of them.