Let's say you implemented your model in python, and want to show it off:
With streamlit, you can simply take your python script, turn the variables you want to change and the plot/dataframes you want to output into streamlit objects. That takes about 5-10 minutes, and then you can already serve your application. It's almost like it's no extra work.
You can write very short amounts of python code and get a nice interactive webapp. It's aimed at, but not exclusively for, exploring data and results. Live reload/etc make development extremely fast.
If that's what you're taking away, we need to improve our marketing copy!
The point of Streamlit is to have a nimble way to create applications, where auto-refresh/hot-reload is part of the developer experience. But the goal of the overall project is to make interactive data apps available to the broad public, not just people who have front-end experience or a front-end developer working on their team.