I've read your comments and it looks like a mess of a codebase, more than a "framework mess". It seems like a bad experience and I would not want to deal with deep inheritance and over-reliance on old/deprecated functionality (computed properties), so... hug.
Controllers are not required for anything except query params mapping.
It's perfectly fine, and I think very common, to load data in components. A rule of thumb is to load in the route only the minimum amount of data for your layout to work.
As for the million of files ... React co-locates template and logic code while ember-cli generates a js/ts file, a hbs file and a test file. It's either 2 to 3 (if you count a test file for the React component) or 1 to 2 (discard test files).
Finding the sweetspot between large components and multiple components is not easy.
For example, it was considered a best practice to apply the presentation-container pattern in React, which means 2 components.
I'm not going to say anything about your claim that JSX is regular javascript in the template.
