IMGUI is great but I always saw it as a more dev-backend debugging tool than a serious production UI framework. Hooks in easily and draws some very convenient visuals.
That's great for bootstrapping, not great for scalability.
Yeah I just wish there was a native UI library that was as easy as ImGui. Everything else is overly complicated. The only other UI framework I know of that is comparably simple is html and css
HTML and CSS are very forgiving for non-compliant code. I can morph the webpage at will by using <div>s everywhere and then manipulating the appearance in CSS. If I want to add data to the dom later on, I have a billion different ways to do so using javascript.
Compared to, say, XAML, where some elements can only have certain types of children, auto-populating data has to go in specific containers, and all the XAML tags map to actual C# classes, It's a much more strict, far less forgiving, and far less flexible syntax
That's great for bootstrapping, not great for scalability.