The problem with an on/off switch is that you have to open the app to change the setting, which means that most people will have it off most of the time. I don't necessarily think the Pear Ring is a better idea than yours; I only raised it to show that other people have tried these low-tech ways to improve dating and have also failed.

If you think about how meeting new people currently works, there's a bit of sizing people up to decide what sort of chances you have or whether they're a creep before you decide whether to go and talk to them - I think that's the crucial aspect your idea is missing.

i thought this is mitigated by setting preferences? I feel like a lot of people get creeped out by mismatches rather real creepy people. So I thought having set some preferences like what the other should like/interests background and so on should prevent meeting creeps

Shared likes and interests are very poor indicators of whether or not the other person is a creep. They're not even very good indicators of whether or not the other person is a good match, to be honest, but at least there's a bit of correlation there.