Web developer of ~20 years here. When I started trying to use Survey123, the first thing I thought to myself was "people have been building web forms and online survey tools for literally decades, and none of them are like this, and that's not a good thing"...
Why has ESRI decided to completely forgo all of the techniques and methods developed over years of software development to establish their own clunky form/survey building system? (i.e., the use of an XLSform, extremely limited functionality and capability, etc)
You can look at just about any other form or survey building software out there to get a sense of how Survey123—as a piece of software—should be designed. Here are a few links to form builders that use a typical, yet intuitive drag and drop GUI, but also allow for an ample amount of both programmatic and visual customization, as well as the capturing of geo-data information and custom database actions.
ESRI should look at some of these over for inspiration:
https://www.gravityforms.com/features/
https://ninjaforms.com/
https://www.zoho.com/forms/
https://wpforms.com/
https://www.google.com/forms/about/
https://formidableforms.com/features/drag-drop-form-builder