While Article 5 is important, its not in a "technical legal mandate" way, and there is a lot more to the alliance than Article 5, there's integrated military command, training, defense strategy, forward deployments to threatened countries, etc.
And there is Article 4 collective regional security, which has ultimately resulted in more NATO combat operations than Article 5, which has been invoked exactly once, even though the former has even less explicit obligation than Article 5.
And there is Article 4 collective regional security, which has ultimately resulted in more NATO combat operations than Article 5, which has been invoked exactly once, even though the former has even less explicit obligation than Article 5.