I wouldn't recommend it to most of my friends or my family for the same reason you mentioned, none of them will utilize those cores.
It just works really well for me and it wildly surpassed my own expectations as I was quite used to the fact that my machine wasn't really usable while I run Kubernetes locally. My workflow used to be:
1. write some code 2. start Kubernetes, wait for it to boot and test the code that I wrote 3. tear it down 4. write some more code 5. repeat
I would be loosing quite a lot of time. Also, while waiting for it to start, I would usually get distracted and start doing something else. Ryzen changed this workflow and boosted my productivity. Now I don't even notice whether k8s is running or not, sometimes I forget it for days :D I can't stress enough how important it is to have a lag free development environment.