Power isn't what determines third party support. Wii and DS achieved massive libraries despite being underpowered, including a bunch of quality exclusives (in addition to a lot of shovel ware). 3DS didn't get quite as much, but still got a decent amount, especially from Japan. What it WILL cost the Switch is high end multiplatform titles, which isn't the same thing. The Switch will only be like the Wii U if it doesn't sell well.
That said, this was said on a show literally called Drunk Tech Review. So this probably shouldn't be analyzed too deeply.