Personally I think both sides of the argument are bogus. There's plenty of adapters for usb-c to lightning and
lightning to usb-c and they're are options (like I use) where you get cables with magnetic ends and plugs that go into your device, which remove one of the biggest points of failures on devices (the power socket, or even pulling it off the table and breaking the screen).
People will still throw away tons of cables, as they'll break them - probably the biggest reason cables get thrown out. Making Apple use usb-c sockets won't stifle competition -(think of all those adapters people will be trying to sell...) - but it will stop Apple charging grossly inflated prices for 1m of cable, because it has a proprietary plug on one end.
Standardisation is a good think for utility items. USB cables have become a utility item. Enough said.