Totally agree with Alan T. It's not the dog, be it a rescue or not, this is about owners who have no control over their dog. If they can't recall, control or are unsure how their dog will react to another dog, they should be on a lead or at least a long line. It's about being responsible for your dog and unfortunately there are too many people who just think they don't have to bother.
The OP mentioned about the woman ranting that her rescue dog had now been put back in the training they had done. What about those of us who have also spent months and years socialising and training our dogs only to have that totally ruined because now our dogs are terrified or become reactive to other dogs? Bonnie is very wary now of other dogs, she screeches or cowers now at approaching dogs, something that has only come about because of her experience with uncontrolled off lead dogs.