On or Off?

Just some food for thought .... When Polly was in heat I walked her in the local park , of course on the lead. On several occasions other dogs would 'naturally' come over and pay her unwanted interest. At one point a dog 'had a go' , if that makes sense? I shouted its owner explaining that she was in season , and his response was 'Well , you shouldn't bring her into the park then'! Now I'm thinking that if my dog is on the lead - im being responsible .. any thoughts?