I believe that in terms of “cultural compatibility” (IMO, VERY important), eastern European people are probably much closer to American values of 40 years ago then the younger people here today.
I’ve heard that this is why some American men are doing this.
They are seeking females who were raised in cultures which have certain values or outlooks on life, which so many modern American women do not have.
Why go halfway around the world to find someone, when there are available females in your own town?