Comment by viktorianer

Rails is a good example of why. One correct place for migrations. One expected controller structure. Validations on the model, callbacks with a defined lifecycle. When the framework defines where things belong, you can write automated rules that catch bad AI output: "no business logic in controllers," "no conditional assertions in tests." Each rule works because Rails narrows what "correct" means.

Frontend has no equivalent constraint. A component can be structured a hundred different ways, and "does it look right" requires vision the model does not have.