A good example is Elite Beat Agents was a fantastically fun rhythm game that could have only existed on the DS and 3DS with the little stylus pen.
You might think “the iPad has a stylus!” But it’s expensive (whereas my friend kept losing his DS Styluses so bought a pack of them for $10) and it doesn’t come with each iPad, so you’d have a fraction of a market, so no such game exists.
Having a CONSISTENT interface for your users is super important. A lot of game devs seem to go for fun second, or maybe never. It took years but just having a game controller seems to be a given for a lot of mainstream Steam games and it helps a lot with games that aren’t really great with a mouse and keyboard (Hollow Knight Silksong sold millions of copies at release)
They are designed to emulate the experience of 8 bit consoles: limited storage, memory, display, palette, etc... While at the same time making developing, distributing and playing games easy: high level language (LUA), built-in development environment, games are tens of kB sized "cartridge" files.