I don't see the purpose of such thought experiments as being to model reality (we've already got a perfectly good actual reality for that), but to simplify it.

You seem to misunderstand what models are for. A model is not the actual thing - thus, we do not say, "Why did you build a scale model of the solar system - we have the actual solar system for that!". Instead, models always leave something out - they abstract away the details we don't think are important to simplify thinking about the problem.

Other than that, I agree.