The second choice most closely resembles why I use my phone sometimes. Personally, I just don’t feel like getting out of bed occasionally, and in those moments its very nice when a game functions as well or better than it does on desktop. Chowdown Showdown is a great example of this. You gotta make sure your screen is in landscape mode before you start but aside from that it works just as well. Runs in browser, seems designed for touch screen play from the ground up.
The second, much more rare reason is (probably the expected one,) that uhhhhhhhhh yknow its easier masturbating in bed than at my desk lmao. That doesn’t come up super often, I’ll admit. Not a lot of the games I’ve found here are that titillating. And SOME games are exceptional enough that sat far back enough in my chair is just fine.
As a practical matter, it’s not something I’d ask for unless I thought it would be relatively easy to accommodate a touch screen control-wise. Spacethumper isn’t a bad example for this. How much do you really need a keyboard for? The biggest hurdle most games face is making them playable in browser on itch. Past that, there’s a lot you can do with three tap controls and a few on-screen buttons.
It depends heavily on how the game plays for me. If it’s something that’s already similar to a mobile game (Fur Food Contest, for instance) then I’d prefer it on mobile. If it’s something more complicated, like Spacethumper or an RPGmaker game, I’d rather have it on the computer.