It would be more robust, avoid more errors and dave time if form fields could be pre filled manually or dynamically. While designing a form, each field would offer a "manual" and a "dynamic" option just like in automations. Hiding (or locking) pre filled fields would also work from the interface so that the pre filled info is guaranteed to be included in the submission.
How does is solve the user problems?
At the moment we pre fill forms and hide fields through the suggested URL strings. As soon as parts of the URL go missing while being shared and shared and copied and pasted, the whole thing no longer works.