I’m typing this story on a keyboard that is also a mouse and also a touchpad … all in one.
When I want to type, I type. When I want to scroll my browser window, I brush two fingers across the keyboard. A three-fingered brush switches windows on my Mac. A single finger moves my cursor, and a tap that isn’t quite a key-depressing typing motion moves my insertion point.
In short, pretty much everything I want to do with the keyboard, I can.
And, pretty much anything I want to do with a mouse or a trackpad, too.