I honestly believe that lifting barbells is the easiest way to improve your strength. But like someone else said, it's only a hammer. And not everything I want to be able to do is pound nails. If I want to keep full range of motion I have to stretch. If I want to keep my aerobic fitness I have to walk and hike. If I want to keep from getting bruises every time I put on a backpack and sleep on quarter inch foam, I have to go backpacking. If I want to do a pullup or pushups I have to do pullups and pushups.
And the other thing with barbell training is that it is very hard on the body. It's easy to overdo it in many ways. It might be great to be strong enough to lift 2x body weight but is it healthy? I feel my health has gotten worse since lifting even though I like lifting and plan to keep doing it until I think I'm "strong enough." Whatever that means to me. It can be very difficult to lift often enough to get the adaptation thing going but not too often that you get sick and stay sick. And getting enough sleep and protein can also be a challenge.