I'd see this as being useful for two reasons:

1. Provision of optional tools: I may use an ai agent differently to all other devs on a team, but it seems useful for me to have access to the same set of project-specific commands, skills & MCP configs that my colleagues do. I amn't forced to use them but I can choose to on a case by case basis.

2. Guardrails: it seems sensible to define a small subset of things you want to dissuade everyone's agents from doing to your code. This is like the agentic extension of coding standards.