Great point. It's also much harder to service which is also true for phones. But we discard phones after a couple of years, cars should be serviceable for decades.
Yet somehow you are far less likely need to service sealed phone...
And are waterproof phones blowing up more often than phones a decade ago?
The scale is few orders of magnitude off
They already run coolant through tesla batteries so they must be water tight to some degree. The connectors got wet in this situation. That's just poor craftsmanship.