Maybe it's because ignorance is bliss!
We attribute "purity" to being "innocent" "unsoiled" or "new".
It's human nature to naturally prefer a (new car) over a used car.
However purity is about thoughts as well as deeds.
In order for some people to feel "special" they need to have or own things that are rare. It's not really about the thing or person they're with but rather how having them or it in their life makes (them feel). Fantasy chosen over reality. I own a unicorn!
The reality is there is no such thing as "perfection".
The "unicorn" eats and craps just like a regular horse does.
(If you were ever able to find one)