If you give any VM all your cores and then your desktop locks up, you played yourself. That wasn't a good idea before docker and it's not a good idea now. I've personally had issues with using file-change-watchers on mounted volumes in some cases but because I limited my VM to half my resources, the underlying OSX was fine and I could still do whatever I needed to do (including killing those containers).
You’re being pedantic. Docker for Mac shouldn’t use the full VM allotment at idle, full stop. Nitpicking the parent for speaking in terms of the host cores instead of the VM cores is off topic and boring.
