DVD -What are they 480i ? 480p ?

[Beachboy]

What is the reason almost every conventional DVD player has the ability to upconvert to 480p (progressive scan) when virtually no SD CRT TV can display 480p? Was it a concession to owners of the first generation HD CRT TV's? I can't imagine anyone with a modern HDTV wanting to use a conventional DVD player with 480p enabled, since "upconverting/HDMI" DVD players are only about $10 more than the cheapie models, and anybody serious about HD viewing is probably going to already have a Blu-Ray player anyway. Just curious.......