They wouldn't be the best selling games on PS4/Xbone/Switch if porting up was really harmful to sales. And MK8 is a Wii U game, Wii U is significantly weaker than the Switch, it's a port up. If they made, say, a Resident Evil game for Switch, then ported it up to PS/Xbox/PC, that would absolutely sell as long as it was a quality game. Obviously which way you convert would vary on a game by game basis, but there's absolutely merit to making Switch the lead platform for certain third party games.
Resident Evil is a good example, as it happened before. RE:Revelations was made for the 3DS, but a port more than a year later on PS3 sold almost as well. If it would've been ported at the same time, not a year later, it probably would've done better.
I also think if Monster Hunter Rise is ported to more powerful platforms it will do well, as it is a great game.