There are countries that have tried austerity and are happy with the results -- Germany, Estonia, Latvia.
Krugman famously disagreed on Estonia last year and was called out by the president of Estonia on Twitter. It was quite funny.
There were numerous articles about Estonia at the time and when I read them, I found myself agreeing with the Estonians. Krugman's argument boils down to measuring the country's GDP at its historical peak and saying that austerity isn't successful if the post-austerity GDP is lower than the peak. The appealing part of his argument is that it's objective. You're looking at some numbers and you can make a decision. The unappealing part is that it doesn't match a common sense view of a country's economic health.
Everybody would agree that if you can achieve the same growth with debt and without debt, you should do it without debt. As another uncontroversial datapoint, everybody would agree that if adding a tiny amount of debt helps you avoid an economic catastrophe, and that the debt can be easily repaid in a reasonable amount of time, then the country should take advantage of the debt.
Beyond those obvious points, there's no clear formula for the benefit of debt. Let's say a country takes on $1 billion of new debt per year, and their GDP is growing by $1 million per year, and if they stopped the debt their GDP would fall by $2 billion but start growing at $500 million/year after that without new debt. Is it worth continuing the debt additions? I guess Krugman would have to say yes because losing any GDP is a sign of failure. Common sense says it's a good deal because you increase your growth so much, you'll catch up to and surpass the high-debt scenario in a few years but have less debt. Of course in real life you can't predict the future with certainty, but it shows a problem in the argument that any immediate drop in GDP is a sign of failure.