you don't seem to understand my point, its not wrong to assume that if mario kart 8 , and zelda wasn't out already, mario odyssia would be selling much better, smash is coming out with most of the major nintendo franchises out, it gonna hurt it a bit. I'm not saying people that are interested in smash are not gonna buy it, but parents buying it as gift have many choices.
It is wrong to think that because if Mario Kart & Zelda weren't out than Switch would have sold significantly less than it has so Mario Odyssey would have been affected as well.
Big games in different genres help diversify a library and push hardware sales, these games do not compete with each other, they complement each other.
When the herd loses its way, the shepard must kill the bull that leads them astray.