Why do people like coding harnesses like opencode etc instead of an IDE?

Just curious - I like to be able to see and manage the scripts my agent is working on. I find stuff like Claude Code and Open Code useful for doing stuff on my linux box but I don't understand why people would use that instead of a dedicated IDE where you can actually see the architecture of your project?

EDIT: Just for clarification, I use Zed when using my local model or Cursor in IDE mode when working on large projects, which is where I chat to the agent.

I only use CLI stuff like OpenCode when running commands on the system itself, like asking it to adjust a server's settings or whatnot.