Many of the YC startups listed there have had more than seed funding. They just didn't announce it. Two others haven't bothered to raise money because they were already profitable and didn't want the distraction.
I believe the same is true for companies in the other incubators; a lot of funding has not been announced.
Being profitable doesn't mean you not should raise money. If anything it's an opportunity to raise money on favorable terms as you don't need VCs.
Four were (ramen) profitable by Demo Day this summer. Two of those did take money from investors. The other two might still at some point. All four have had offers.
Also note that for several of these (like Frogmetrics, Picwing, and others), pageviews aren't the best metric of "success" because the website isn't the product.
Note that this is not the most up to date compete.com numbers. The latest came out today.