But Nintendo games are usually strictly sold on Switch consoles. Wouldn't the fact Sega games are usually multi-platform to give them the edge?
That's the theory but the fact is not like that ... Nintendo first party games in Switch/Wii/3DS/NDS really sold that much, beating the sales of other multi platform games.
For example just take a look at Top 10 Best-Selling Racing Games of All Time
1. Mario Kart 8 Deluxe (70 million)
2. Mario Kart Wii (37 million)
3. Mario Kart DS (23 million)
4. Mario Kart 7 (19 million)
5. Need for Speed: Most Wanted (16 million)
6. Need for Speed: Underground (15 million)
7. Gran Turismo 3: A-Spec (14.89 million)
8. Gran Turismo 4 (11.75 million)
9. Need for Speed: Underground 2 (11 million)
10. Gran Turismo 5 (10 million)
Nintendo dominated the top 4. Also only 3 games of 10 were multi platforms (Need for Speed series) since Mario Kart and Gran Turismo were exclusive to Nintendo / Playstation consoles.
The console where the game's released was also a factor.
The top 4 were released on Nintendo's best selling consoles/handhelds (Switch, Wii, NDS, 3DS).
The irony is Mario Kart 8 Deluxe for Nintendo Switch was a remake of Mario Kart 8 for Wii U which doesn't even make it into the Top 10.
Being released on the Switch does make a difference, a lot.
Also I don't know whether it's a factor or not: most of Nintendo fans never pirate their games.
Gamers who wanted to try Nintendo games might, but not the die-hard Nintendo fans.
That's why they're always welcoming Nintendo classic catalogue back to their newest consoles.