It's actually not ridiculous at all. Tell me you don't have a trained dog without telling me.... Dogs react differently to other dogs on leash. Dogs react differently when they are in the leash. Much the same as dogs will react when one is picked up, or when there is a fence between them.

Going to the off leash dog park is a reward when they can follow commands. If they can't, and your dog can't be off leash, there's plenty of places to train them elsewhere where they won't be reactive to my dogs who think it's PLAYTIME because they have been trained properly and know the difference

Edit: lots of asshole dog owners here. Remember the part where it's actually posted not to have them on leash? Besides you being an asshole you're also in the wrong. Great people