Why do some discontinued Rolex models keep trading above retail years later?...

https://astro-wiki.win/index.php/Is_the_Steel_Pepsi_GMT-Master_II_126710BLRO_Discontinued_or_Just_Hard_to_Get%3F

Why do some discontinued Rolex models keep trading above retail years later? Take the Kermit 16610LV and the Hulk 116610LV—both have built steady demand despite being out of production