The only country that would need to fear a defensive alliance, is the country that wants to have the freedom to attack without having to worry about retaliation.
Suppose all inhabitants of the street I live in make a defensive alliance saying "if someone breaks into the house of any one of us, then all other members will immediately come to that person's aid". Suppose even that I don't get along with anyone in my street.
Do you think this pact would bother me in the slightest? That it would worry me in the slightest?
Why would it, unless I actually plan on breaking into one or more of their homes?
This supposed fear it has of NATO, is actually extremely telling concerning what kind of regime we are dealing with.
And that tell shows us in fact also EXACTLY why NATO is so important.
Because in the east, we clearly DO have a superpower nation that does NOT have good intentions. That DOES want to be free to invade and attack countries without consequence.
If it didn't have this desire, then it would have nothing to fear of an alliance like NATO.
Article 5 is the infamous article that, when invoked, scrambles (in principle) all member states to take military action.
It is clearly noted that article 5 ONLY applies in case of a member being attacked.
It is entirely meaningless if a member state is the one that does the attack, or suffers a retaliation of an act of aggression of itself.
So what is there to fear of NATO, unless one actually attacks a member state first?
What you're failing to consider is that, very often, nations can and do start wars while setting up the circumstances in such a way as to make it look like the other side started it. Not that I'm saying that's the case here, but I think your argument basically amounts to nothing more than "Trust me, bro. You have nothing to fear." I believe it's somewhat naive to expect other countries to accept such promises on blind faith.
Now we have people saying "let's avoid direct confrontation and let Putin just have Ukraine". If it weren't for the western support (by request of Ukraine), Kiev would have fallen already and Ukraine as a country would already be part of Russia. Or a Belarus 2.0 at best.
But as history has shown us.... even as schoolyard bullies show us... appeasing a bully, thinking he'll stop by letting him have your lunch money once, is never a good idea. In fact, it only signals them that you are a coward and won't stand in their way the next time either. So they will just march on. As Hitler did. And as Putin would. He is already eyeing Moldavia. His operatives are already there, stirring things up just like they did in eastern Ukraine leading up to 2014.
History shows us a lot of things. It's also showed us that even "bullies" are human beings with the ability to reason and change. They are not like dogs who attack if they sense fear or weakness, which is an unfortunate perception held by too many Westerners. If nothing else, we might take heed from the ancient war proverb, "Know your enemy." To perceive an enemy in such a one-dimensional, simplistic manner like that seems counterproductive.
"Appeasement" probably started more at Locarno and continued on, not necessarily because they were cowards, but more because they were broke. I don't think Hitler would have seen them as cowards either, but he probably didn't believe that Britain or France cared so much about Czechoslovakia or Poland to declare war over it. But he, too, didn't know his enemy very well.
Still, a large part of the reason the war went on as long as it did was because the Western Allies really didn't do anything at the start. They declared war, and then just sat around waiting for the Germans to attack. And then France buckled so quickly. That was the real disaster, not appeasement. They had the Germans outnumbered and outgunned, yet they collapsed so fast. Britain held out against the German onslaught, but they were kind of stuck at that point, since they were in no position to do anything about what the Germans had already done and were continuing to do. But then, Hitler chose to invade the USSR and declare war on the USA, so that was another case where he failed to know his enemy and made some real boneheaded decisions.
Stalin has been viewed by many as a "bully," so in the case of the Eastern Front, it might be thought of as "bully vs. bully."