I disagree that most apps are CRUD. To the contrary, most apps starting out as naive CRUD have complex implicit constraints related to eg. in what state you can

I disagree that most apps are CRUD. To the contrary, most apps starting out as naive CRUD have complex implicit constraints related to eg. in what state you can modify resources in a particular way. Even for CRUD apps with simple master/detail data relationships it doesn't make sense to tie your domain design to network requests.