I have used Unity and Blender MCPs and I am not sure I am seeing why this is not a needed concept (or is a bad implementation).

If Unity updates the version (and the MCP server with it) - my agents immediately see the new surface. They weren't trained on the features of the new version of Unity, but they know about them as soon as they are added.

Context bloat is a thing - but you only turn on the MCP servers for what you are actually working with. If I am only in Blender, I don't need the Unity MCP. So it can be disabled.

These are just two example pieces of software but the concept applies to all of them with MCPs.