Also, please note that in my original comment I'm talking about the future - after the collapse of Russia, in a few decades. Can you guarantee that the world will not need to deal with another Trump in a situation where the MAD doctrine stopped working?
And as for currently, don't you think the US is not making "desperate threats" simply because it has absolute no need to? In a parallel universe where Russo-Sino alliance conventional military was much more advanced than the US, what would the US do if the alliance absorbed Mexico or Canada, deploying (for protection, of course) tens of thousands of people along with huge piles of weapons on their territory? Can you trust the US not to make "desperate threats" then?
I can't.
Especially because there's only one country that developed and used nuclear weapons against civilians. In that context, even a statement from a clown of a president about "fire and fury" is something really dangerous. And since we already had to deal with a clown, it's really not that much of a stretch to fear that an actual madman gets elected sometime down the road.
Threatening with conventional arms is not the same as threatening to use nuclear arms. Many countries threaten to use their military - yet Russia is going as far to threaten the offensive use of nukes. I’m discussing the reality of now not some theoretical future/parallel universe as what’s the point? Russia is doing what Russia is now and that’s the problem.
Are you old enough to be sure you will be dead in 20 years? If not, then making sure we won't be all dying in a "fire and fury" would be the point. Otherwise, I guess, you have the luxury of not thinking about "future/parallel universe" that might just one day become the reality.