For the same reason as why you shouldn't have a service that locates where sex offenders/ex inmates, this service shouldn't exist. So many things can go wrong with something like this...
Yeah, you can be worried about the consequences to the sex offender. There's a valid argument there. But I'm worried about the potential consequences to my daughters.
And the situations aren't comparable at all. I get to be a sex offender by doing something. I get on the wrong side of this new site by annoying just one person.