Of course, you could argue that smart pointers shouldn't be a thing, but I think most C++ developers would disagree given the significant advantage of essentially automatic ownership management, at least for tree-like structures (cycles are more complicated, as always).
What would you propose as a simpler solution? Many languages have GC, which is arguably the simpler solution you speak of, but would be unacceptable in C++, since the large majority of applications it is used for require predictable low-latency responses. Manually managing pointers is how you do things in C, but has it's own sets of problems, since it can't be checked in any way by the compiler, so things like forgetting to free, double free, use after free, etc, are common, while with smart pointers these errors are impossible.