One of our biggest internal projects at work is our web based accounting system. If there is a bug that is not a technical issue but an accounting issue, i cant do anything (i have no clue about accounting). If the bug touches multiple layers of the software (backend and frontend) our application developers are sometimes busy for days. Thats slows down development and is expensive.
With Lona, and the Lona widgets i created for our accounting system, i can give them a very simple, abstract and pythonic API for common tasks like "show an table and then update it", "show a progressbar with an abort button" or "show a popup with 3 buttons". The code is more readable for everyone involved, and the application developers can now solve most of their problems on their own.
Performance: Yes you are right, you have to sacrifice performance for this approach to web, but performance is in this kind of applications no problem. CPU time is cheap these days, developer time is expensive. We are a small team.
Your example code @ https://lona-web.org/#what-is-lona imperatively builds a web-page... you still are writing the same amount of code but you're adding another step. When you write the html it's declared and it's done, there is no extra processing like there is when you write a program to produce another program.
This is cool though, clearly it has some real utility for you, I'm curious though; how does it improve the web development experience? How does it make you more efficient?