I didn't believe you, then I went and checked.
https://www.cnet.com/news/usb-4-will-resurrect-those-useful-...
Apparently all the hubs that have multiple USB-C ports are running USB 2 over them, or you can just use them for power delivery.
I am suddenly very happy that none of my other devices except for my USB-C hub, actually uses USB-C, I'd be limited to the ports that came on the computer!
Thunderbolt docks can do it, they just run multiple USB controllers on board, one for each port, but indeed, it USB-C 3.1 as it stands today doesn't support hubs.
A quick google search returns https://satechi.net/collections/usb-type-c/products/type-c-m... which isn't what I have, but it's more of the same.
My complaint about usb-c hubs, when I was looking for one a year ago is I couldn't find one that did 4k60, gigabit ethernet, and 2 or more usb 3.0 plugs. This has led me to plugging in two cables instead of one for years. If my monitor had a gigabit ethernet plug, I'd be set, because it outputs a bunch of usb (2) ports.
Hopefully USB 4 will make it possible.
A USB hub is just one USB port in and N out. There is no such thing for USB-c.
You can't even chain those adapters. The USB-c 'in' port that you plug power into? No data on that line. Just power.
And some of those adapters send the wrong voltage to USB-2 devices. Had a hell of a time with my keyboard and mouse until I started plugging the power directly into the computer.
I guess we'll have to wait another few years.
I can see why this all is though, the limitations are going to be insane.
The weirdest one is that I at least expected those 'hubs' that have the port breakouts for everything to at least be able to take data in through both ports, but that doesn't work either. You can only plug a power brick into the USB-c female port.
https://superuser.com/q/1381139/122042
https://mjtsai.com/blog/2017/10/14/the-impossible-dream-of-u...
Did you read the protocol specification? (It's freely available, with no paywall or even login wall.) The protocol does support a USB-C hub. Actually protocols, since there are three separate protocols involved, each on its own set of wires: USB 2.0, USB 3.x, and USB-PD. Each of them has its own support for USB hubs. The hub support for USB 2.0 and USB 3.x is the same as in the older USB hubs with the USB-A and USB-B plugs and sockets; only USB-PD is new (and has long chapters on how power delivery works through hubs in several different scenarios).
The only gotcha is that Thunderbolt 3 does not support a USB 3.x hub (but this is fixed by its successor USB4); this is worked around by including a full PCIe USB 3.x host on the Thunderbolt 3 device, since Thunderbolt 3 can pass through PCIe and Displayport at the same time (USB4 adds USB 3.x to the passthrough).
There is no such thing as a USB-C hub. The protocol doesn't support it. That's one really concrete way that USB-C is inferior. I think I heard rumors that the proposed replacement fixes that, but Thunderbolt 3+USB-C is inferior that way.
It's also easier to snap off. That's two. Yes, it's better in a lot of objective ways, but there are also non-imaginary ways in which it's a pretty substantial compromise.
Maybe we should do a longbet on whether you're willing to talk smack about T3 once T4 hardware comes out. Because I bet you will.