The thing I've been trying to figure out over the years is just who loves all the contestant backstories.
My theory:
Producers realize, either consciously or subconsciously, that game shows are more compelling when the viewer has a rooting interest in the contestant. Which is true: I think even the most jaded of us will perk up our ears when we learn that a contestant is from the same hometown or enjoys the same hobby.
Problem is, a basic "where are you from, what do you do" will always only captivate the small fraction of the viewing audience that shares that very specific biographical detail. And there are very few contestants who can win over lots of strangers with naturally likable personalities that will shine through a twenty-second television interview (especially if the host isn't experienced at interviewing people).
So the way to try to entice the audience to sit through the entire episode -- which is important if there isn't much game to play along with -- is to create an emotional rooting interest by sharing the most root-worthy biographical details of a contestant's life. "Everybody loves a person who rescues dogs, so here's a person who rescues dogs! Stay tuned to see if this dog rescuer wins!"
And I think it does work -- in moderation. I was once with a non–game show friend and we were watching
American Ninja Warrior -- a show that's especially guilty of this practice -- and after each two-minute package about an athlete who overcame some kind of adversity, he would be more invested in their run... and more excited/devastated when they succeeded/failed.
The problem is that when every contestant on every episode of a show is accompanied by a feel-good package, and when every competition show introduces every competitor with a feel-good package, the impact is diminished and the viewer is annoyed by being overexposed to the manipulation.