Various Mario and Zelda titles have been fantastic after dozens of games.
I should have brought up Mario. Many of the "sequels" of the game were sequels in name only, as they belonged to an entirely new genre and platform. Let's be honest, what does "Mario Kart" have to do with the original Mario except being used as a selling point? Even having said that, the most recent Mario games (Super Mario Wii and Super Mario Maker) have been a return to the roots. All Super Mario Maker literally is doing giving people the ability to make (and play community-created) levels for the original Mario games, which could already be done, but in a much more complicated (and potentially illegal) manner.
The Zelda franchise is more or less the same. I mean you could technically call Starward Rogue, The Last Federation, and SBR part of the "AI War" series, because it's all from the same universe; but I don't think that would very honest of you.
I meant sequels in a more literal sense, though you brought up some great examples.
I think he brought up Mario Kart because it's the 8th game in the Mario Kart series, not because of the main Mario series.
Besides, honestly, I think people worry WAY too much about having every game do something "new". That, when you really think about it, is a tough order to manage even in games that aren't really part of a series. Even with something like Starward there's nothing truly "new" about the formula it's using or the gameplay. Instead, we just tried to make it GOOD instead of hyper-unique.
And I think that's the most important thing. And really, I think it's possible to get TOO unique. I mean, like, Mario games; when I buy a Mario platformer, I expect it to play like a damn Mario platformer. Something like Mario Galaxy ended up just irritating me, adding unnecessary motion controls to the mix (enough to kill most games for me) and doing some irritating things with the level design (that whole planet idea got on my nerves fast). First Mario platformer that I've ever NOT liked. I know the game did well and lots of people do like it, but it still fits as an example for me. It was them trying to fix something that didn't need fixing.
Or, worse, there's the new Star Fox... I'm not even going to talk too much about that, but that was another "do something new even though they didn't have to" situation that blew the whole game to hell.
I'd really rather that devs go with something that works and will be fun, well-balanced, and full of quality, rather than worry about being "new" just for the sake of being new.