>>725573806 (OP)
On consoles, you'll want everything physical if you really care about the games you're buying.
Sure, if you buy a digital game for $2.99 on sale, it doesn't matter, but if you're going to spend $80 on Mario Kart World, then you'll want the full game in the "cartridge", it's that simple.
Game key cards are digital games, so you won't buy them. Digital products can only be purchased on open platforms.
For example, I bought an ebook yesterday on a website. This ebook is now on my PC's SSD, on my ebook reader, and in the cloud. I have three copies of this ebook, so I know that my access to it is pretty secure for years and years to come, and I can open it on any device that reads epubs.
You can't do that with a digital copy of Mario Kart World. You'll only be able to download that copy on a Switch 2 with your account logged in, and that's it. Game Key Cards at least allow you to move the game to other accounts, but you still depend on Nintendo's servers and the eshop that will one day stop providing you with your $80 game (pic related).