I would be very confident this is down to the headphone jack issue.
A lot of people I know have opted to skip the iPhone 7 because they aren't convinced by the lack of headphones.
Common myths I've heard:
1) People think you have to use the Apple wireless headphones and no other type works. Where as in reality any bluetooth headphones work.
2) People think you can't connect analogue headphones to the phone at all, whereas in reality it came with an adaptor dongle which most people will probably leave connected permanently to a pair of headphones anyway.
The only real issue I could see with it is that you can't charge and listen to headphones at the same time. That's pretty stupid and will mess up a lot of people's setups with older cars and so on.