This is actually not true.
Article Five states that an attack on one becomes an attack on all. This wording is very specific, and they wrote it with this wording intentionally, to get people to be willing to agree to join.
It does not require counterattacks or declarations of war, merely that you consider an attack on a member an attack on you.
How do people respond to different sorts of attacks? How can they theoretically respond if they so choose? These are the kinds of games being played in Putin's head.
That's a key phrase.
Pariah, possibly, but I don't think a party like the AfD would particularly care about pariah status. I'll also remind you that Article 5 has been triggered once, by George W Bush after 9/11. He then wanted to invade Iraq, and did not receive the full support of NATO members.
It's just not that simple, unfortunately.