Immediate mode and polling are not the same thing. With Dear ImGui you own the event loop so you can draw as frequently or infrequently as you want. It is not necessary to draw 60 times per second when nothing is happening.
Dear ImGui's sample code currently does draw every frame even when nothing is happening. Omar has said that he would eventually like to change this and it's on his roadmap, but it's low priority because he is currently targeting game industry users and doesn't want to attract a lot more users in other areas that will add to his support load and dilute his focus. [1]
He also has said the same thing about accessibility and fancy theming. These features are good examples of why "the stuff that dear-imgui does" is not a good definition of immediate mode. People often assume that anything Dear Imgui doesn't do is hard or impossible for any immediate mode API, but that's far from the truth.
Omar is only one guy. He has a target audience in mind and is not trying to satisfy all use cases at once. You have to remember that when comparing Dear ImGui to a framework like Qt or SwiftUI or whatever that has hundreds if not thousands of developers contributing to it.
Dear ImGui's sample code currently does draw every frame even when nothing is happening. Omar has said that he would eventually like to change this and it's on his roadmap, but it's low priority because he is currently targeting game industry users and doesn't want to attract a lot more users in other areas that will add to his support load and dilute his focus. [1]
He also has said the same thing about accessibility and fancy theming. These features are good examples of why "the stuff that dear-imgui does" is not a good definition of immediate mode. People often assume that anything Dear Imgui doesn't do is hard or impossible for any immediate mode API, but that's far from the truth.
Omar is only one guy. He has a target audience in mind and is not trying to satisfy all use cases at once. You have to remember that when comparing Dear ImGui to a framework like Qt or SwiftUI or whatever that has hundreds if not thousands of developers contributing to it.
[1] https://github.com/ocornut/imgui/issues/7892