So many things can go wrong on-leash. I can say from experience it’s always my fault if there’s an on-leash incident with one of my dogs. The leash causes tension, can get tangled and creates an unsafe space if there is an issue. Don’t even get me started on flexi leads. If you want to properly introduce your dog to another it should be done in a secure area where they can be free to walk away if they choose. I also want to note, my dogs are under no obligation to meet every person or dog they come in contact with. Just yesterday on the ferry a family insisted I let Piper meet their already scared dog. It felt unsafe so I politely declined and kept walking. It’s simple. I don’t know if they were put off, and don’t really care. I did what I thought was best for Piper. It’s okay to say no. Socializing doesn’t mean forcing your dog to meet every dog they see. It means exposure.
Here is an excellent article to read with lot’s of great information: Talking to Other Dog Owners–Tread Carefully