Update thanks to thethatfox:
Physical game cards may also not actually contain the game:
Nintendo Switch 2 Game-Key Card Overview
Game-key cards are different from regular game cards, because they don’t contain the full game data. Instead, the game-key card is your "key" to downloading the full game to your system via the internet.
Update 2: There is probably a difference in Game-key cards and card that contain real game data. So we don't know right now how often these game-key cards are used or if nintendo is using them.
I get why, but I don't have to like it.
It's not widely talked about, partially because Nintendo doesn't like it talked about, but the Switch cart format makes very little sense in a lot of the same ways some of the PSP and Vita storage didn't make sense. They are very expensive for the specs and quite small. I can only imagine this version of the carts is even more expensive, since they openly say they're targeting faster speeds and standard SD cards are out of spec.
But let me be clear, that is nuts. They are effectively selling you a M2 SSD with each physical game purchase. It's terrible value compared with a BluRay, for everyone involved.
It's still a weird step that both breaks with tradition and moves things towards digital distribution forcibly, much in the way that shipping optical drives as an optional add-on did for the PS5. Having a massive collection of physical Switch games I can't be on board, and it's not the only additional expense they're adding (paid back compat upgrades, Nintendo? WTF?).