Given that literally every other smartphone on the market has a USB-C port, i'd say this is not the reason why Apple used a non-standard connector, failing (voluntarily) to comply with European interoperability laws/standards.
Sep 2012 for lightning shipped, and USB-C not ratified as a standard until Aug 2014.
Apple was not exactly unaware of these developments, as they have repeatedly signed the memorandums of understanding surrounding charger interoperability, according to wikipedia.
... or because Lightning has a commercial "preferable profile" - it's another form of lock-in, and at the hardware level no less; such an extremely desirable feature, from a commercial perspective, is very, very hard to give up. It would open the door to a world where phone accessories are effectively universal, and surely we can't have that.
whereas USB micro-A is 6.85*1.8mm².
The difference might not be very noticeable, but USB-C is has around 3 times the area of USB micro-A.
So no idea about RF engineer comparisons, but Apple seems to have stopped waiting for consensus on what USB-C would be, in wanting to ship something thin before Samsung and Google and LG could even design something thin, by almost 2 years.
Aug 2014: usb-c standard written, so no devices yet.
this ordering keeps being overlooked in comments.
I wonder if some research suggests a port change would stall phone upgrades among enough users of earlier models, and that phone upgrades are lucrative.
USB has to go on devices where the port already represent a sizable fraction of the cost, and there is a race to the bottom to whoever will produce the least expensive parts, and of course, it is shit. If lightning was standard, we would probably see a lot more failures, simply because not everyone has the same quality requirements as Apple.
Of course, USB doesn't have te be terrible, but when you compare USB to lightning, you compare a mixed bag of good and bad parts to only good parts. To be fair, you should only compare USB implementations from reputable, expensive brands against lightning.
In this context USB-C has failed hilariously, given how much do reliable full-featured USB4 cables cost.
Not sure if it's measured as significant, but it's the sort of thing that RF engineering concerns itself with (preventing anything from detuning antennas or otherwise raising the noise floor).