Perhaps that's the compromise then? in handheld mode party chat works via inline mic, in console mode you have to use Bluetooth, the option for non Bluetooth is to use a phone app which is effectively allowing your phone to act as a Bluetooth link for headphones connected to it
I'd assume if you use a non 3.5mm jack phone you'd have a Bluetooth headset, in which case that would connect to the switch?
In a way it future proofs Nintendo if Bluetooth takes off as a headphone option, at which point they can patch the OS to allow Bluetooth headsets in the handheld mode, or still use the 3.5mm jack
could be wishful thinking, but if I'm right then no wonder the communication on voice chat has been so vague and miscommunicated