Hi Roman,
Thank you for your idea!
As you might be aware, fetching data for recently released Reactive Web Apps works exactly the same way as in Mobile apps. Here's an excerpt from our blog post, Reactive Web: The Next Generation of Web Apps, that describes Data fetching.
Data fetching

Instead of using Preparation, you’ll find screen data directly below the screen. Screen data is composed of aggregates, data actions, and variables. Aggregates provide easy access to entities’ data, while data actions can be used for more advanced cases, like fetching data from external services. All these are executed asynchronously and in parallel. This will improve your app’s UX, since there is no need to wait for all data to arrive before starting to display the page.
Thank you again for sharing your ideas!
Cheers!