edit: I also looked for a usb A hub with usb-c upstream, still no luck and stuck with a hub+power adapter and dinky otg a-to-c.
Let's assume the hub requests 19V from the upstream port. Unless it has built-in, variable, per-port voltage regulation, it will not be able to respond to power requests from the downstream devices if they differ from what is coming from the upstream port.
This isn't a problem when providing USB-A ports because you either request 5V from upstream and pass it through or request a higher voltage and have a single 5V regulator and pass its output to the downstream ports.
This is all possible, it's just a HUGE pain in the ass (and costs a lot) to design that way. The problem is you essentially end up with potentially a giant, VERY expensive USB hub. And no one wants to spend $400 on a USB hub.
You could also theoretically use 10Gbit Ethernet to transfer data from your phone but we don't go around putting SFP slots on phones because we don't want every single cable or charger to cost $100 and be more complex (thus more prone to failure) than needed.
The ask for the 'really expensive' $400 one has vastly more options and capabilities than the traditional USB hub. It's basically a Thunderbolt hub with even more complexity, so it's not unreasonable to think those would be damn expensive.
I'm honestly not sure why no one has made a standard USB2.0 Type-C hub. There's really nothing stopping you from doing it. I guess maybe because it could be confusing for a consumer? I agree, that's a huge issue with Type-C right now. It's very unclear by looking at the port (or the cable) what it's actually capable of. If you're lucky there will be a tiny symbol indicating some subset of functionality, but often times there isn't.