How many of those users have only an iPhone?

If the iPhone had an USB-C connector, I could pretty much carry a single cable and charger for my laptop, my tablet, and my phone. So unless there is zero overlap between iPhone users and users of anything else, the point is moot.

Even worse, Apple stopped bundling a charger with their phones over three years ago. Instead, they ship a Lightning to USB-C cable, but they bundle an USB-C charger only for a year after the release of the iPhone X, effectively forcing their customers to buy USB-C hardware anyway.

Sure, you can now carry 1 less cable. That's a win, but it's not some monumental change people try to make it out to be. When I travel I will still carry multiple cables since I need to usually charge more than one device at a time. But now they can be the same cable.

They can be, but in practice you’ll want a cable capable of at least 60 W for the laptop. So now you either have to carry all the same high power cable (more expensive and wasteful) or give up on the benefit of having one type of cable to begin with.