For point of comparison, most heterosexual dating apps steadfastly refuse to add weight filters, despite them being the most demanded filters (aside from height). Why? Usually there are excuses about how it's impossible to implement or that the people who want weight filters are confused about what they want, but somehow LGBT dating apps all are able to add weight filters without any difficulty or controversy. Why weight filters are considered an undesirable feature in heterosexual dating apps is left as an exercise to the reader.
And dating apps could, in principle, tell the people who want race filters to pound sand just as much as they tell the people who want weight filters to pound sand. The fact that they don't is a political choice.
I don't get it, why is that?
I think it's because we know that our weight is completely up to us and that a failure of keeping the weight that is desirable to others is a failure of ourselves. It's a thing we deep down know is our own fault and it scares us. As for height, it's not my fault I'm short or tall, if you don't like it, meh, I didn't screw up or anything.
Dating apps have artificially forced people into making superficial choices.