I'm aware of options like SDL, Raylib et al; despite that, indie is still dominated by editor-heavy tools, like Unity. I've been shipping games for nearly 20y;

I'm aware of options like SDL, Raylib et al; despite that, indie is still dominated by editor-heavy tools, like Unity. I've been shipping games for nearly 20y; indie and AAA, and good Editors always win. Even programmer-focused pipelines tend to evolve into designer and artist focused pipelines over time. It's simple: Dear Imgui doesn't solve the problem of rapidly iterating on an asset from Blender/Maya/Houdini; or from rapidly iterating on level design and scripting; or rapidly iterating on sound import and design; or... Over the course of development many indie studios end up reinventing tools that are already cheap or freely available.