Itch is not exactly a platform for IO games, sure you can put them there, but it hosts a lot of other stuff such as experimental and "extremely indie" games, software tools... It is a platform, storefront and community for things game developers make.

IO games on the other hand are usually characterised by being (sometimes only allegedly) multiplayer web browser games with super minimal friction, just open a page and play.

Put differently, I wouldn't call a supermarket a toothpaste store even though that is indeed an item supermarkets sell.

Maybe this was meant as joke, but this isn't true at all.