You quoted a pretty good definition of a startup. So why not do the obvious thing, and call something a startup iff it meets that definition? Why encourage using a different and more generic word "business", if that doesn't clarify anything?

Next we're going to get a blogpost claiming that a startup with massive growth but no revenue model shouldn't get to call itself a business (because real businesses make profit!!). And so we go in circles again and again.

Yes, many people don't know the difference between a business, a business spin-off and a startup. The solution is to label things accurately, and to explain the difference when you notice people are confused. The solution is not to use a less accurate label in protest of people using labels inaccurately!