Having preferences is still a problem (a real problem) when your preferences are utterly unrealistic and ridiculous. Such as not-so-attractive 5'2" women demanding to only date men who are 6'4", or 60-year-old men refusing to date women older than 30.
Of course, I guess you could argue that people like this really shouldn't be in relationships to begin with, so it's better if they maintain their preferences and standards and refuse to budge, effectively self-opting out of the dating pool.
Why are unrealistic preferences a problem for anyone but the person with the unrealistic preferences?
The only way someone else’s standards become a problem for you is when you feel entitled to that person’s attraction (“I’m a 7 and she’s a 6, therefore she should give me a chance. But she only talks to 9s, the nerve!”). But you’re not actually entitled to anyone’s attraction, so that’s on you, not on them.
>Why are unrealistic preferences a problem for anyone but the person with the unrealistic preferences?
Did you read my 2nd paragraph?
>The only way someone else’s standards become a problem for you
For me personally, that's right. For society as a whole, suppose that everyone suddenly decided they would only date model-beautiful people. Pretty soon, everyone is terminally single, no one forms families or has children, and society dies out within a couple of generations (unless a different way of raising children is found, such as keeping them all in government-run institutions, but this still entails a radical change to society).
Of course, I guess you could argue that people like this really shouldn't be in relationships to begin with, so it's better if they maintain their preferences and standards and refuse to budge, effectively self-opting out of the dating pool.