Good article taking apart that “three million toothbrushes” story and concluding that it’s pretty certain to be merely a hypothetical scenario rather than something that actually happened. Much of the reasoning matches what I thought as well.
Edit: There is now a confirmation from Fortinet about this being a hypothetical scenario.
Yes, it would have been hilarious. And we are still heading towards a world where millions of vulnerable toasters can do serious damage. But we aren’t just there yet.