I disagree apy. If it were a small problem you would be correct that we should call the person’s Rov or Rebbetzin. But the problem is two-fold; 1, it is a very unfortunately a massive widespread problem (not affecting b”H MOST frum people, but nevertheless all too many) and 2, many people don’t have a close enough connection to a Rov or Rebbetzin who will proactively seek to individually remedy the problem.
And I do believe the kol koreh’s do have a positive effect on the public. True, not everyone will take heed. But if even a FEW people do change as a result (and it WILL help with some), it is well worth the effort.