I disagree. I was in college during the Wii's run, and it was the only console my friends and I played together (though several of us had other consoles). Games like Smash Bros, Super Mario Strikers, and even Wii Tennis were at least weekly events.

Edit to add: I was at a party a month ago, and the hosts had their Wii available. People were playing then, too. I think maybe WiiU didn't offer what people wanted. At least among my experiences, multiplayer was vital.