I'd like to offer a slightly different perspective, although I absolutely see the danger of mission creep. This is a quote that always sticks with me. German defence minister Peter Struck, years ago when he was rationalizing the war in Afghanistan—Germany and NATO being in Afghanistan—said that German security depended on the security of the Hindu Kush mountains. He meant that security threats defy borders and regions nowadays.
When we talk about cybersecurity you cannot say that we're just worried about cybersecurity in the north Atlantic region. When we worry about terrorism it's the same. NATO has engaged in out-of-area operations. I would argue that many of the global threats we face are transnational threats, so we have to view them as such. Whereas I agree we have to be very careful, that's why I talk about working with regional organizations. NATO shouldn't be everywhere. If you can work with other actors on the ground, that should be the option you take.