"I'm referring, of course, to the proverbial frog that, placed in a pot of cold water that is gradually heated, never realizes the danger it's in and is boiled alive. Real frogs will, in fact, jump out of the pot -- but never mind. The hypothetical boiled frog is a useful metaphor for a very real problem: the difficulty of responding to disasters that creep up on you a bit at a time."
If this becomes a "hypothetical" frog, a "proverbial" frog, a "useful metaphor" to get across a point, then it enters the company of "the streets were paved with gold" or "his eyes were bigger than his stomach" in being a useful way of conveying an idea, although no one thinks the image itself is literally true. At it can exit the realm of the "cautionary revelation from the world of science" that it typically occupies in political speeches or, sigh, the documentary An Inconvenient Truth. It's still a cliche, but you can't have everything. I had not previously thought of Paul Krugman as a peacemaker or placater, as opposed to a provocateur, but he may now have shown a new field of achievement.