> I like how Google AI Studio allows one to delete sections and they are then no longer part of the context. Not possible in Claude, ChatGPT or Gemini, I think there one can only delete the last response.

I have the same peeve. My assumption is the ability to freely edit context is seen as not intuitive for most users - LLM products want to keep the illusion of a classic chat UI where that kind of editing doesn't make sense. I do wish ChatGPT & co had a pro or advanced mode that was more similar to Google AI Studio.