There are two clear scenarios where this makes sense:
1. When the client code is content-addressed, and that content addressing is enforced by the browser
e.g. https://ipfs.io/ipfs/Qmfgh... with browsers supporting dweb protocols natively as Firefox is working on
2. When the web ui is served over localhost from an app you've downloaded and can independently verify. This could be a local only app, or it could be a p2p app.
1. When the client code is content-addressed, and that content addressing is enforced by the browser e.g. https://ipfs.io/ipfs/Qmfgh... with browsers supporting dweb protocols natively as Firefox is working on
2. When the web ui is served over localhost from an app you've downloaded and can independently verify. This could be a local only app, or it could be a p2p app.