True multithreading is just that. It will scale on as many cores as you can give it, just like it does in server land and so on. However, whether implementing that is the same as anything else? I don't know. Threadripper apparently is two Ryzen CPUs basically glued together. This could present a problem, as not only do you need support for the threading but you also need support for multiple CPUs. IE - getting the software to recognise there are two CPUs there and not just one. Unless of course it presents itself as one? who knows yet?
But in the past dual CPU setups have not been the same as one CPU. They will do well where they are seen, but otherwise you will drop back to one CPU. It's obviously not a problem for Windows, because Windows NT used to support more than one CPU as did 2k and on, but yeah it definitely presents another problem.
In server land? these will perform as they should straight away. In desktop land? yeah, that might be why they are not in the same socket/class as Ryzen 7 CPUs.
Again AMD need to get the support in. And that means a lot of hard work. Hopefully they can pull it off