Earlier quoted context omitted.
Sure, but you could detect zip codes that are under a certain length and/or area, keep combining them until they are large enough. Zip codes are just a starting point, the concept would still apply. Group people into sufficiently large chunks, only reveal their chunk. It could be a grid instead if that makes more sense, but I imagine zip codes make use of borders along rivers and other forms of convenience.
There's usually always a catch. Your try to make it less easy to find someone also makes it less good for the intended use case. Suddenly the app can only tell you if someone is in the same town or not because we combined the heck out of zips. But the you realize that at the edges of whatever combination you chose you can find if someone is on one side or another of those areas. And these areas have borders on many s…
It's been a long time since I've done online dating, and back then long-form OKCupid profiles were the norm, but instead of a distance radius, I always wished could draw a shape of interest roughly correlated with my local subway map and places that were convenient to walk to.