Another problem is that USB-A ports are dirt cheap and simple to implement, so hub makers feel like "leaving free IO on the table" by not sprinkling them on everything. Whereas each "decent" USB-C port has enough complexity to think twice about adding it.
Nevertheless, there are a couple of options. Try searching for "USB-C only hub". You will get some results, but they are basically the identical product (same IO card), just with different housings. So you can pretty much count with these specs: 1 USB-C in for power, 3–4 USB-C out, 5 or 10Gbps each, Power Delivery at various wattages. No video support.
I have one of these on my desk right now, it's from the brand "Minisopuru", I get power and four USB-C "3.2 Gen 2" ports. It's fine. But like I said, it's no Thunderbolt, and no video support, so I have to "waste" the other port on my MacBook just for my external display.
There are also Thunderbolt / USB4 devices which will give you a bonkers amount of IO, including good TB / USB-C ports usually (plus some USB-A of course, as a spit in the face – so you'd need to ignore those). But these are not hubs, they are docks, which is a different product class entirely (big and heavy, more expensive, dedicated power supply).
Something I've been doing recently to salvage the USB-A ports I still begrudgingly encounter, while continuing to (force myself to) upgrade all my devices to type-C, are these: [0]. 1-to-1 USB-A male to USB-C female adapters. I just stick them in all USB-A ports I encounter, leave them there all the time, and move on with my life. It's a bit bulky and looks kinda stupid, but it basically gives me USB-C everywhere I need (including work-issued PCs and docking stations) for just a couple of bucks. For low-bandwidth devices like headphones, keyboard / mice / gamepads, or even my phone, it works perfectly fine.
[0] – https://www.amazon.com/UGREEN-Adapter-10Gbps-Converter-Samsu...
https://www.aliexpress.com/item/1005008363288681.html
But you can also find them in smaller hub form.
It's the power consumption.
IIRC, USB-C has a base power per port of 15W (5V @ 3A) with just basic CC resistors. USB 2 starts at 0.5W (5V @ 0.1A) and is only supposed to allow 2.5W (5V @ 0.5A) after negotiation. USB 3 is 4.5W (5V @ .900A).
Note that the Caldigit hub linked in a sibling has a power supply of 20V @ 9A. That's 180W!