This just reads like a godot advertisement...it only has good things to say about godot and only bad things to say about any other library. It's really hard to take the article seriously with so much blatant bias. It also seems to leave out any technical information that a developer using the engine would want to know, like how well it integrates with existing code, what paradigms it uses compared to other UI engines…
I made this comment when someone was talking about using GLFW and IMGUI to make an application with a openGL window and I think it applies here too, because it is easy to overlook the things that you will eventually need that are not trivial to add once you go down the road of using tools made for only very basic UIs. "I would bet that the easiest thing would be FLTK. You can use system colors and make an openGL wind…
One of the few weaknesses of IMGUI is theming though. Don't expect to create one of those fancy Material-themed apps with animations, it's primarily intended for creating dry, technical tools of the likes of game engines and modelling/animation tools. It's more in the mindset of creating 'tools' rather than 'apps', and it really depends on your usecase.