Funny, on both my work and home mac desktops, I use the Magic Touchpad as my primary input device even while sitting at a desk. So I suppose I disagree with this statement.
What about precision? do you think that the touchpad is more precise than a good mouse on a good mousepad? I'm not asking you if YOU are more "productive" using a touchpad, I'm asking you if you think that if we compare a proficient regular mouse user vs a proficient Mac touchpad user we'll notice a significant difference that'll make us think that Mac touchpads are the way to go?
I don't think so. I think the factor that weighs more is user preference, heavily influenced by marketing.
Also with gestures you have way more stuff you can do with a touchpad then just moving a mouse and clicking stuff.
And let's not forget the smaller travel distance of your hand when you go from keyboard to touchpad, as when you go from keyboard to mouse, or back.
I have a Logitech MX Anywhere 2. I love that mouse. It is fantastic and when I'm working on my home laptop I use it every day, if I'm in desktop mode that is. And I prefer it over the touchpad.
But when I work on the 'work' Macbook Pro (2015), then I use the touchpad all the way. It's just so much better and intuitive compared to using a regular mouse.
I would never want to use a mouse again! Yes, for me an Apple touchpad is way superior to a mouse. If you don't get that, that's fine. We all have our blindspots.
Whose marketing? Apple doesn't push the Magic Trackpad over the Magic Mouse. If you buy an iMac online, the mouse is their pre-selected input accessory.
Same with rotating in Preview and easy smooth zooming on webpages.