If I have a partially filled-out form that is really the query box for a search backend, and I hit back, why at the browser level should my flow be interrupted?

If I have a partially filled-out form that is really the query box for a search backend, and I hit back, why at the browser level should my flow be interrupted? That content was ephemeral. It's an application-level question, not a system question. Can only be answered with semantic knowledge of the importance of the user input.