With a pointer you treat the screen as a continuous space. With Saka Key's link clicking method (for the lack of a better term) you're selecting out of a discreet set of keys. I'm not sure what the implications are, but I feel like the difference is qualitative.
On a good trackpad you don’t actually need much visual feedback because the response is very predictable. You can make a short movement and click more quickly than you can press a couple of keys.
Saka Key looks to be both slower and more complex than navigating using a trackpad (especially once you take scrolling into account).