Don’t get me wrong. Apple removing audio jack was the biggest facepalm in smartphone history. And you can thank it for not being able to make an upgrade without sacrificing audio jack (and SD card too :/). But USB-C is getting standardized everywhere now (laptops, smartphones, etc.). What makes USB-C earphones not worth the switch?
I love USB-C for charging and data and display. But it does not replace 3.5mm. Aside from the things mentioned so far in the comments here, a fundamental problem is that now headphones need DACs in them.
https://en.wikipedia.org/wiki/USB-C#Audio_Adapter_Accessory_Mode
That increases the cost of headphones and introduces a point of failure and makes things more complicated for the end user. It’s just not worth it.