Custom Post Types - html instead php?

With classic block based themes one have to work with php based custom post types, e.g. defined and registered manually or thru a plugin like “CPT UI”. With FSE (and Cwicly), isn’t better to work as follows:

  1. Add custom post type within theme.json (e.g. “customTemplates”: [
    “name”: “book”,
    “title”: “book page”,
    “postTypes”: [
  2. Add a respective (empty) html to the templates Folder: book.html

Now one is able to add a standard template “book” as a template
When creating pages or post, one have to change the template within the editor the new team template

The only disadvantage I see, is, if there are a lot of entries (posts) who are e.g. blogs, and other categories with a lot of entries, they are all mixed up in the dashboard

Am I missing something?

I guess I miss the following: with template only approach one cannot have different sets of e.g. categories for e.g. blog posts and “books”, I guess I have to read more about what still has to be done per CPT or not, or how to do that now fully html based