Because the dating scene is like the hiring scene. There are 100 applicants for every position and in that situation it makes sense to use very noisy low value signals that are cheap.
And just like hiring where there are great employers with silly hiring practices there are great partners with silly filtering rules. And you can cut yourself off from a large part of the market or play the game.
Unlike the potential employer or partner I'm not going to use a silly filter as my filter.
I think you're giving far too much credit to the reasoning abilities of people who filter their dates this way. They're not carefully coming up with heuristics to optimize their "application process". It's just plain ordinary shallowness.
But that aside, your entire analogy is based on the idea that you need to "win" iPhone Girl. What makes her worth winning, and why doesn't she need to win you?
You're allowed to have criteria too. One of mine is that I won't be with someone who has poor judgement. It's the reason I don't date women who are into astrology, or choose their partners based on the brand of their phone.
To use your analogy, iPhone Girl is a job that pays $30K a year while demanding 70 hours per week. That's not good enough for me, I don't care how nice her campus is.
And just like hiring where there are great employers with silly hiring practices there are great partners with silly filtering rules. And you can cut yourself off from a large part of the market or play the game.
Unlike the potential employer or partner I'm not going to use a silly filter as my filter.