If you want to find a way to not defend an ally, you'll always find one :)
NATO treaty itself does not talk about rapid response forces, joint bases and so on. All of that comes beyond the treaty. What stops key states from retreating back to basic treaty and then finding an excuse when Article 5 comes? E.g. if Russia comes as non-marked „rebels“?
But there was no defense alliance between NATO and Ukraine, right?
Maybe NATO has also weak wording in the treaty itself. So ask yourself - why did Ukraine want so badly to be accepted into it? Why is Russia opposing NATO expansion so much?
Budapest treaty is pretty damn close to defence alliance in it's wording.
Why did Baltic states or Poland wanted into NATO so much? It's one more treaty you can show to media when shit hits the fan. One more treaty your supporters can use debating governments for help.
In reality, if Russia attacks a NATO member, it won't be automatic full-on NATO response. It will still be debates. But certain people will be much more uncomfortable saying „no we won't defend NATO allies“. Yet some will still say it.
Russia wants it's own NATO, with black jack and hookers. And countries joining the real NATO obviously won't join theirs.
NATO treaty itself does not talk about rapid response forces, joint bases and so on. All of that comes beyond the treaty. What stops key states from retreating back to basic treaty and then finding an excuse when Article 5 comes? E.g. if Russia comes as non-marked „rebels“?