Long story short:

Nintendo sold about 4-5x the amount of Kirby, Pikmin, Metroid and Xenoblade games on Switch than they did on WiiU and 3DS combined.

Input of a Xeno-series fan: duh. WiiU didn’t sell well and despite Xenoblade Chronicles X (pronounced cross, same name as the main character) being good, it was no system seller. And Xenoblade Chronicles 3D didn’t sell well either, being one of only 11 New3DS games.