use the bed only for sleeping.
Someone might sit on the edge while putting on shoes, place a suitcase nearby, or briefly put clothing or other belongings on the bed.
The runner creates a designated area where some of these activities can take place.
Because the runner is smaller and easier to remove than a duvet or comforter, it can also be more practical to clean or replace when necessary.
That doesn’t mean it should be assumed to be perfectly clean, however. As with any textile in a hotel room,