... what I’m challenging you to do is to avoid reducing conversations to “pick two” when sometimes the right person with the right idea might well be able to see a way to achieve all three.
I think "sometimes" is the key word in that statement. There may be a very limited number of edge-cases where all three have been achieved. But I wouldn't go changing any rule based on edge-cases.
We should try to keep an open mind towards the possibility of achieving all three, without fooling ourselves into thinking it is always going to work that way.
"Pick two" becomes more than just a myth, perpetuated by those who don't want to do work, when it is backed by decades of common experience, amongst a large number of project managers from all over the world.