True, but it's still a cost-benefit calculation, and even with the major surgery you're basically catching up with the previously paid premiums. I believe it's better in pet care to set aside the money yourself if you can. Obviously if you can handle the monthly cost plus what the insurance doesn't cover and don't want to risk a major expenditure, have at it.
We have Brittanys, Bonnie & Clyde. Previously our Brittany Willow got grievously ill at age 10, and the vets both locally and at Angell Memorial in Boston really never gave us a diagnosis. Great compassionate care, just no diagnosis. After 5 figure$ of care without much change we eventually put her down. Didn't have insurance, and we thought with the new Brittany pups we'd get the insurance. (*see below) Doing the calculation, though, we saw that we were paying $1300 annually for insurance and we still had substantial out-of-pocket via deductibles plus what wasn't covered by the insurance. The gamble is that your pet won't need such a thing more than once.
*So ... we got the two Brittanys in September 2019, 8 weeks old. Wife was walking them on the driveway about a week after they arrived, planned to but hadn't bought the pet insurance yet. They're weaving all over the place, and she accidentally steps on Clyde's leg. Doh!! Four pins (also 5 figure$) later and he's now doing great. Decide on the pet insurance as soon as you commit to the pet, and don't procrastinate. Our 1 week delay was costly.