You also can't plug in an ethernet cable or use a floppy disk! How useless!
Eh, you joke, but if you REALLY REALLY need to get data from a floppy disk to a PC/MacBook? It might take a while and cost a lot, but you CAN get accessories to make it happen. And that's true of basically any media you can think of. Slide reader? Sure. Record player? Yeah, you can find one with USB.
With an iPad your option is... finding a PC. It's just straight-up never gonna happen without one. I'm not saying that you need to have 100% backwards compatibility- for what it's worth I think the single USBC port on recent MacBooks is fine- but you need
something. It's not that you need the ability to access any one media in particular but that with USB there's enough interconnection and backwards compatibility that you can access anything when you need to.
Honestly, people who say they don't need USB* are like people who say you don't need a car in LA- either they don't actually ever do anything important enough to need be anywhere at any particular time, or what they're actually saying is that they're using someone else's car. Being
that person might be fine if you're just working on personal stuff, but it becomes unprofessional and childish pretty quickly when you're working in the real world.
*or some other kind of standardized connector