I agree with you, but just a small nit: > First off, templates are the opposite of opaque due to the fundamental requirement that the implementation be visible

I agree with you, but just a small nit: > First off, templates are the opposite of opaque due to the fundamental requirement that the implementation be visible to every translation unit using a template. That's not strictly true, you can have an implementation hidden in a separate TU, as long as that TU instantiates the template for all template arguments that the users are going to use.