So, I had heard this was a thing, but had not encountered it myself until recently.
A couple of months ago, I decided to dip my toe into the world of online dating. And it didn't take long to see women's profiles where height isn't just a preference, but an absolute (dis)qualifier ("Under 5'10", do not message"; "Must be tall"; "No one under 6' please" etc.).
This strikes me as odd. I could never and would never write something like "BMI < 25 only." And yet, height is completely out of a person's control, whereas weight is not.
I understand we all have preferences. I have preferences. But I like to think none of my preferences are absolute, binary statements. As in, I would never date this particular person because of this one characteristic. I might prefer a slim person, yet I married an overweight person -- because she was funny, smart, creative - basically she checked almost all my boxes, and I try to look at a person in their totality. To put it another way, I might be attracted to X, but that doesn't rule out Y or Z.
In my own profile, I try to imply my preferences rather than lead with them ("looking for someone to go on runs with me..."). I think this is much better.
And I assure you, I write all of this without bitterness. It's more a curiosity of why this form of discrimination is seemingly socially acceptable. Or at least, acceptable in the dimension of online dating.