Comment by Gigachad

Yes, you can't expose multiple computers at the same time on v4, but you certainly can expose one, in exactly the same UI you exposed v6. And then that one you exposed has full access to the local network beyond the firewall to expose the rest.

The argument seems silly almost like "I deliberately shot myself in the foot, but with v4 I could only shoot one foot at a time while v6 lets me shoot both". The answer is to just not shoot yourself in the foot, since you have to make a deliberate effort to do this in the first place, just not doing that is the answer.