Not true in the slightest. USB-C headphones can be used on any USB-C equipped device, including the MacBooks. Lightning ONLY works on the phone.
USB-C is a valid replacement for the headphone jack because it's a universal port (just like the headphone jack!). Lightning is NOT a valid replacement because it's proprietary. Proprietary headphones are utterly useless.
Lightning can also be used on iPads and iPods. But it can't be used on Macs, nor is there yet an adapter for USB-C, Thunderbolt, nor 3.5mm -- and that's a problem.
That said, USB-C is hardly a universal port at the moment. When I can walk into a 7-11 at 3 in the morning and buy a USB-C cable, maybe your point will have some merit. At the moment, USB-C is just as pointless as Lightning. Further, Lightning headphones don't necessarily have to be useless. For starters, if I were spending any significant money on headphones, I wouldn't invest in fixed Lightning NOR USB-C headphones. I would make sure I could easily swap the cable for anything I needed. The Audeze Sine headphones are a perfect example of the only thing I would buy at this juncture, or at a minimum, I would insist on a 3.5mm removable cable which could take any kind of DAC equipped cable.
But moreover, Lightning isn't meant to be a replacement, and for that matter, USB-C isn't a valid replacement either. The replacement for the headphone jack is wireless -- wifi or BT. Lightning or USB-C are there as wired options for those who need the highest quality signal available. And that's exactly what Apple has provided -- native wireless output, with the option of Lightning, or adapting the output to 3.5mm, or frankly anything else. Bluetooth is now the universal port for audio, and it's only a matter of time before all new audio products provide BT as a standard way to connect listening devices. At some point, no phone will have a Lightning or USB-C port, and instead do everything via wireless, or magnetic inductive connectors like the SmartConnector where a wire is preferable. That's the future, and that's what Apple is preparing us for.