> Because obviously the changes that you make in the gui are completely isolated from the changes you make on the server.

In my experience, that is almost never the case. Often, the frontend requires a new endpoint or a modification to an existing endpoint. If you don't coordinate this change, you end up with a non-functional PR that cannot even be tested. Same happens when the backend proposes an endpoint change that affects the frontend.

We have moved the frontend and backend to the same repo to make coordination and testing of such cases simpler.