Interesting that these games are significantly smaller on Switch. However, I think that is only part of what is going on. I know that devs have complained that their games are too big for the Switch before.
I do believe some games with high fidelity are too big for Switch cards. Let's say a game like The Last of US 2 which assets are so high quality that it came with two discs, one to install and another to play. Not needed to be said these games wouldn't be playable on Switch anyway as the console itself cannot render the game
I can't think any game that can run on Switch that can't be compressed in a 30 GB file, unless devs come with a very good explanation of why they cannot compress the game for whatever reason
So when developers are saying something about the games being too big to cards is most likely to be... well lies. They just don't want to spend money using more expensive storage.