So now you have presentation logic, tightly coupled, spread over two places. You need to jump between two codebases to even have a clue about what is rendering on the page.
There's an example on their website where the header of a table is defined in the frontend, and the body is returned by the backend. If I wanted something as simple as switching the order of the columns, I'd actually need to create a new version of my backend endpoint, release it, change the frontend to use the new endpoint, then delete the old one. That sounds crazy to me.
