Unfortunately, even if there was, they wouldn't have Thunderbolt so it would limit the external display options. Hopefully when USB4 starts rolling out it'll be a different story.
So I think lack of thunderbolt comes down to manufacturers not wanting to pay as much for their AMD R&D and keep costs down with simple, budget motherboards.
Or, if you needed Thunderbolt 3, you could just wait until USB 4 is commonplace, which is basically Thunderbolt 3 + some more.
[1]: https://www.asrock.com/mb/AMD/X570%20Phantom%20Gaming-ITXTB3... (there are more, and even ATX boards, first one I could find).
It's an understandable restriction if you already bought a Thunderbolt screen and need a new computer that's compatible with it, but requiring Thunderbolt case I might get a screen that needs it later is very far down my priority list of computer features.
You're only giving up the data part of TB3.
There's actually no difference here whatsoever on the display-only side of things.
(side note, USB 3.2 achieves up to 20Gb/s, not 10Gb/s, and TB3 is also realistically only 20Gb/s as well unless you're sticking to the super short 0.5m cables)
But good to know about the display connection being the same. I was under the assumption that the increased data rate of TB3 could be used for DisplayPort connection too.
https://www.cablematters.com/pc-1220-126-usb-c-triple-4k-dis...
If you want displays and all your other dock stuff combined under a single cable, that's where you're better off with Thunderbolt, yes. The USB-C docks can do some of this (I think with DisplayLink) but not quite as well.
A Thunderbolt dock doesn't limit your display choices like the comment I replied to was talking about though, you'd just use any normal DisplayPort screen. Worst case without it you're plugging in separate display cables in addition to a non-video USB hub.