I like this idea, a lot. I think it is necessary having something like this. I always say that CPT are okay if we need more than one item with a custom structure. When a CPT is set, you get the chance of adding as many items as you need. So if this is what you need, it is more than fine to use CPT.

However, when you need a specific page with a custom structure, CPT is no longer a valid solution, since you would still have the chance of adding many items and it would break the original requeriment.

I haven't had the chance of taking a look at Papi, but I believe something like this is a necessary approach.

Thanks a lot for you hard work and for contributing this big!