I don't see any facts in that link that refute the metaphor. Old experiments at 0.2 °C per minute show the frog dying, while newer experiments at 1.1 °C per min

I don't see any facts in that link that refute the metaphor. Old experiments at 0.2 °C per minute show the frog dying, while newer experiments at 1.1 °C per minute have the frog jumping to safety. It was already noted that the speed of the heating affected the result in 1888.