The vast majority of users don’t carry a bunch of dongles around.
It’s just true. What are most people doing?
Zoom, Excel, PowerPoint, Browser, Slack, etc.
But that means when I carry the laptop around I have to carry a dongle for the mouse or not use the mouse. It depends. The mouse is ergonomic and easier on my hands than the trackpad, so I prefer to carry it. It's just one dongle, and I'm already carrying the mouse, so not too bad.
I also need USB 2 for my Yubikey, which is USB 2.0.
Before I had USB headsets but that would be 3 USB 2.0 devices and my portable hub only accepts two, so I ditched them and switched to the old wired iphone earbuds since they are light and stateless.
That also means I have to give up my ergonomic keyboard and use the flat keyboard, but usually that's OK unless I am on a long trip. If I'm on a long trip, I'll want that ergonomic keyboard after a lot of typing at which point it's 3 USB 2.0 devices and then I need to bring the powered hub with its own adaptor. I can leave that where I'm staying and just take the mouse to the coffee shop. But this adds complexity.
All in all, it's doable, I'm not complaining that it is an insurmountable obstacle, but I would prefer a computer that was a bit thicker and heavier but had more ports built just to reduce the overall complexity of the setup and not worry if I brought everything with me. When you compare the weight of the usb hub and its adaptor to the extra weight added by adding a few more ports, I'd prefer the laptop to be a bit less demanding in input requirements. To me that would make for a more mobile solution overall.
But honestly these are minor issues.
In practice it leads to a significantly worse product for the vast majority of users, for the benefit of the minority that falls in the pro crowd and is able to get all their work done solely through USB-C ports.
But the Apple Pro crowd users tend to include a lot of audio/video professionals who have a lot of expensive devices they tend to connect through USB-A, HDMI, etc, Photographers who were big fans of the SD card readers, and business people who didn’t really need pro devices but could afford them, and were fan of the video outputs for connecting to projectors and monitors, and maybe even LAN inputs because many offices tend to discourage WiFi networks.
I think Apples big mistake was a category mistake. If they had made the MacBook or MacBook Air all USB-C, for example, there wouldn’t have been too much of an outcry. But the MacBook Pro line is the same one that carried a FW 400 port years after FW800 had been released and even after FW itself was kinda dead besides certain niche applications (which tended to be popular with Apple pro users).