But it's harder to have component composition. Consider also lists and adding/removing items and so on, juggling all of it gets insanely complex and requires MVC or MVVM patterns like with backbone.js
But now we're back at "Not everyone is building complex UIs like google sheets". I agree with the underlying sentiment of this thread: overengineering is way more common than underengineering.
Eventually each crud form evolves into something more complex, the bar is set higher today, we expect pagination, filtering, search, inline editing, grids, instant validation, auto-save, push notifications, state sync, ... that's not a complex UI nowadays, it's expected. Not sure what a non-complex UI looks like.