No, not all of them. Some are already profitable when they apply, and a few more make it to profitability just on what we give them. But the distinction is not a sharp one: most of the profitable companies would take money on sufficiently good terms.
Though I don't mention this explicitly in the article, Demo Day isn't just for raising money. It's a good way to get mindshare too, because the people in the audience are so influential. So even the startups for whom raising money is not a top priority usually try hard to be impressive on DDay.