It isn't at all unusual for flights anywhere in the world to stop along the way and for the airline to describe these as "direct", and in some cases for passengers to have to deplane while cleaning and refuelling takes place at an intermediate stop on very long haul journeys (LON-SYD) for example). In these cases the actual plane always continues unless there is a mechanical issue.

However people from elsewhere in the world are often taken by surprise by the US-based airlines who routinely schedule equipment changes at an intermediate stop, so the only thing that continues is the flight number. I know that on international flights this is sometimes the only way to comply with fifth freedom regulations without using over-large planes for one segment of the journey, but what is the justification for doing it on domestics? On the face of it it seems designed to deliberately mislead would-be passengers.