But in practice you end up with skills that depend on other skills, or a skill that assumes specific instructions are already loaded, conflicting skills, versioning and supply chain issues - and suddenly you need dependency resolution.
I've built a package-manager approach for this (APM - github.com/microsoft/apm) and the thing that surprised me most was how quickly even small teams end up with config sprawl - and how much a manifest that travels with the project helps.
The "too small for a repo" thing is real, but one pattern that works is having a monorepo per dev team or org with all skills and building jointly over there.