Which is nonsense.

Sony have been including waterproof headphone sockets on their phones for years and also magnetic power connections up until recently where they've now ditched the mag connector for waterproof micro USB. Previously the USB port was only waterproof with a flap with a seal around it's edge.

Rumour has it the next model is waterproof USB-C as Sony has also released USB-C memory sticks.

I've a Z1c and a Z3c tablet and can attest to the waterproof abilities of those. I ride a bike in all weathers with a Z1c on the handlebar and it's been totally waterproof except for when I pulled the mag connector out. The connector is stuck on with what looks like double sided tape. I stuck it back with 'Stormsure' tent glue.