I grew up with working Border collies and had a lot of experience with dogs all my life but in my mid-30s, twenty-plus years ago, I had on my hands a fear-aggressive GSDx rescue that I had no idea how to handle because I'd never dealt with the issue before. She was fine with me always and I've never lacked confidence with any dog, but I was at the time not sure how to help this dog. After she attacked my neighbor, I was on the verge of having her put down, but my vet suggested a really good trainer (they were not common then, and the internet was in its infancy) and he provided my knowledge and insight and techniques to help her handle stress and be safe. It wasn't confidence or "leadership skills" I needed with that dog because I already had that; it was insight and a deeper understanding of what was going on with her. I got that now and I'm thankful.
Seriously, this guy saved that dog and she lived a full and wonderful life with me for another 12 years, and I learned a lot both from that trainer and from my dog. None of us were born with an innate capacity to deal with problems our dogs might have and sometimes we need help! So we learn, and we pass it on and help when we can. Easy dogs are easy but we don't learn much from them. It's the problem dogs we learn from (sometimes with help and insight from other people) if we are smart and reach out when we need to.