Do you mean dpkg/rpm/apt/yum/pacman/etc? These require root access and per-manager, and often in practice even per distribution version, specific instructions. Not meaning to bash them, I still like them, but the actual problem of ensuring stable interfaces is not solved. Conan and these and other package managers are only automata that provide value under the hypothesis of stable interfaces.

C++ has way to many failure modes regarding linking and generally consuming libraries (ABI issues, build system agnosticity). Conan addresses those compatibility issues in a holistic way through package ids, which are basically hashes over anything relevant.