kinto.core why isn't ID in the Colander Schema?

In our case we are using kinto.core on a resource where we want to enforce the ID.
[This](https://github.com/Kinto/kinto/blob/master/kinto/core/resource/__init__.py#L322-L323) prevent us to do that in the deserialize of the colander method.

Read kinto/core/resource/__init__.py around lines 322-323 and inspect the Colander deserialization path. Determine why the ID is excluded from schema validation and whether that prevents resources from enforcing it; done means the intended validation behavior is defined and verified with an appropriate test.

Written by the indexing model from the issue text.