[lavabiopsy]

The thing is those are likely to be simple GUIs. Those are a great use case for immediate mode. But try it with something that has a lot of:

- Wrapping text labels

- Widgets that are similar to CSS flexbox where the size of elements depends on other elements

- List/tree widgets or text editor widgets with large datasets in them

And then you will notice performance tanks. Think of trying to build a text editor that way, if you opened a 5MB text file, you would have to rescan the whole 5MB and compute reflow for it every time.