Validation does need to be done on both sides. But validations on the client side means no round trips and you can do validations even when you’re not online. Also even if the content is “static”, if you don’t have access to the network, how do you do simple things like display totals from service charges, a receipt of all the items delivered - propane as deliveries and tank repairs, alarm installation or at home nurse care where they had a checklist?

Even with CRUD apps you need to display dynamic content based on user interaction.

I used to be big in native apps, until having seen too many examples of what used to be done in VB/Acess back in the day.

So you haven’t seen the poor performance of ASP.Net Web Forms with the huge hidden field to maintain state and redrawing the screen for every interaction and a network round trip?