"Err...most of the time." There were still some dragons that just didn't want to be ridden.

"They used to wreck out homes all the time. Fly in, steal our food, burn down our houses. But we weren't about to let them win! So we kept rebuilding and fighting until someone finally figured out how to get them to work with us. Turns out they were stealing our food to feed to this dragon the size of a mountain! So we fought that dragon and killed it! And now the other dragons are our friends...most of them."

Of course she wasn't giving Hiccup the credit he deserved, but he'd had more then his share over the years.