These results are not too surprising to me. Sure the Switch version is by far the inferior one, but people are not buying Switch for top performance. Instead here are why people like the Switch version:
1. 2D games are more appealing to Switch owners.
2. A lot of people want to play this game on the go. Switch is the only way to do that.
3. Collectors prefer carts to discs, because they are more durable and easier to store.
4. People are currently more in the habit of playing their Switch regularly. PS4 and XB1 are old and gamers want to move on to a new console after a while. If the last game they were playing was on Switch (like Smash Bros), then the next game will probably be on Switch too, all things being equal. It's about habit.
Put all of that and you can see why Switch is not going to be hampered by PS5 and Scarlett either. There are a lot of people out there that don't really care that much about performance (including every person who likes Minecraft). Instead they just want a system with a lot of fun games on it and at a decent price. That is Switch.