I don't understand the first point as a claimed security level with a specific threat model. The second point, about deactivated points, is equally true of serverside encryption --- again, assume keys stored clientside, but encryption code run serverside (in fact, it can be true in applications that don't encrypt at all).

If I have a 0day for your backend stack, or you fail to upgrade a dependency, I might get RCE on your backend server and install an exfiltration system, but I would not necessarily be able to pivot to changing the frontend bundle on the static CDN without compromising the CI/CD and code review system, which (hopefully) uses isolated credentials and has strong audit logs. A threat model where even a persistent or long-running infection on backend servers allows user content (if not metadata) to remain opaque can be useful.