The Recents view shows all of the pictures in the Photos Library by date added. It's the same on every iPhone, iPad, and Mac, and it's something you can always count on and can't change or mess up.
I know that if I send some pictures to my iPhone, maybe by iCloud or AirDrop or something, and I want to find out if they actually made it there, yet, I can look at Recents without worrying that they somehow moved somewhere else. Anyway, that's the value of they're not being moved out of Recents.
Keep in mind that albums don't actually contain pictures-- albums are lists of pictures you like to see together. So a picture can be in several albums, on several album lists, really, without taking up any more space. So a picture can be seen in the Recents album and in the Aunt Bertha album, but there's really only one picture, and it's on two lists.