Another benefit to the alliance is the cooperation on military equipment. They make most of the worlds arms to one standard so if a war were to break out they can often influence who will be the victor by giving or denying spare parts and replacements. Also they know the strengths and weaknesses of said arms so if faced by them have a distinct advantage in the electronic warfare aspects do to the denial of source codes to many of the users that they believe are unreliable or untrustworthy.
So, no. NATO is not irrelevant.