Re: @ the AC, re: wireless headphones.
For some people, lack of 3.5mm is minor inconvenience - they'll just use the converter included the box.
For a smaller number of people, whose usage patterns mean they often want to use earbuds whilst charging the phone AND don't want to use Bluetooth AND don't want to buy a 3rd party Charge+Listen dongle, the inconvenience is greater.
Now, anyone considering using this phone will weigh up this potential inconvenience against other factors. Switching to Android is inconvenient if you're used to iOS, and buying to a bigger, more expensive iPhone is inconvenient if you want a compact phone and not spend too much. In this case, we can actually put numbers in here: iPhone SE 2020 is £420, iPhone SE 2020 plus two Charge+Listen dongles (one for work, one for home) is £435. So, substantially mitigating this inconvenience costs £15.
Pragmatically, one would assume that this extra cost will only cause someone to buy a different phone if there was already a close contender on their shortlist. Since we're talking a phone used for many things and not an MP3 player dedicated to this one task, there will be many other factors for them to consider. Thus the sentiment 'No 3.5mm no sale' appears overly dogmatic unless you're considering two otherwise very similar phones.