To be clear, I am pro USB-C, but I do get the arguments from the other side.

If I have a lightning cable and a device with a lightning port, I can plug it in and not really think much about it.

If I have a device with a USB-C port and a USB-C cable, I have no idea whether I can charge at full speed or even charge at all.

As an example, I plug my Xbox controller into my PC via USB-C. It keeps it fully charged. Recently I tried to plug in my USB-C headset into the same cable and it didn’t charge at all. In fact my headset died shortly after I unplugged it (after “charging” it all night), which was a bit of a pain. Turns out it can charge with my laptop charger or my iPad charger but not the Xbox cable plugged into my PC.

Maybe this isn’t a totally fair comparison, but it’s my personal experience.

The general problem with USB-C is that the connectors support multiple different protocols, cables are allowed to not be of sufficient quality for all use-cases (the worst example is probably high-bitrate cases like cables for computer monitors) including high power charging. Similarly, the devices on either end needn’t support all the potential protocols/uses. Furthermore, many USB-C devices that are sold are low quality and can damage devices that are plugged into them by failing to follow the specification (eg delivering too much power). So, if you’re a consumer and you have two devices with USB-C ports, and a cable with USB-C on both ends, connecting the two together might either work fine, work with poor performance (without telling you this), not work, or damage your device. And there isn’t really a good way to tell this will happen.

Lightning isn’t that much better though. You can get lightning to USB-C cables so you can plug into various bad devices and have other USB-C problems, though you likely won’t try to plug into a monitor for example.

There’s maybe an argument to be made about the ports too. I think it would be harder to clean dust/fluff out of a USB-C port and maybe they could be more fragile too because of the spike in the middle of the port.

It still seems to me like Apple probably also like that they have a lot more control over lightning. And they already have USB-C on iPads and computers so they clearly don’t think it is totally terrible. But there are a lot more iPhones in the world than other Apple devices and I can imagine eg Apple having to spend a load of money on customer support, etc, due to the USB-C issues, or getting blamed when things go wrong because of the cable or device on the other end.

I think it would be better if the possibility of connecting two devices with a cable implied that they would work together, but I’m not sure how that could be done without either more ports or more expensive cables/charging bricks. And I don’t know why a USB-like organisation would have more success at ensuring things follow the standards than USB currently have.