Comparing anything to the Wii era is setting up for failure, Nintendo sold over 250 million units of hardware between Wii & DS, that is a feat that had never been remotely close to happening before that and will never happen again.
NES+Game & Watch, SNES+Gameboy, N64+GB Color, Gamecube+GBA, Wii U+3DS each did 85-115 million and Switch is on pace to do similar numbers.
The Wii + DS combo was a complete monster. The PS3 + 360 + PSP numbers combined were close to matching the Wii + DS combo but still fell short.
For the Switch, 17 million in a year (or fiscal year) is nothing to scoff at. The install base will continue growing as games continue being developed and released. No, the Switch is not the Wii, but it doesn't have to in order to be considered successful.