I think it should be fine as long as the cat was always kept indoors and it gets enough attention and space to play. They should be treated differently to how many people treat their outside cats.
My indoors cat is now 5 years old and very much like how you described Buddy. He wanders around the house, likes to play and likes people (even strangers). He gives all the signals of being very happy and calm, isn’t easily scared or startled. Sometimes it seems his character is more like that of a dog than of a cat.
Many people have cats that are outside 20+ hours a day and don’t like ‘socializing’ with people. My parents had a few cats like that as well when I grew up and I don’t see the point of having one like that. They aren’t beneficial for the environment and don’t offer much as a pet either.
What wars did NATO start then? Don’t confuse countries in NATO with NATO itself.