Sure, but what you're saying can be be interpreted both charitably and not. The charitable interpretation is for scenarios like focus wrap-around in modals. It's possible to navigate by tabbing over focusable elements hidden behind the modal until you're in the modal again and it's sufficiently difficult to make focus work 100% correctly without extensive testing.

But if you're trying to argue in court that your submit button can't be activated without a mouse because doing so is too hard, that's likely not going to pass muster, since virtually every other website on earth can easily figure out how to do it.