Most comments here are about how painful eye-tracking as a mouse replacement is. What if instead it was just used for the 1-2 most often used buttons on a site

Most comments here are about how painful eye-tracking as a mouse replacement is. What if instead it was just used for the 1-2 most often used buttons on a site. For example, here on HN - to go back to the main page. Or, on gmail - to press compose. Once gaze in the general area is detected, the affordance can be highlighted, at which point press Enter would cause navigation. I feel that <4 buttons are the ones that are pressed 80% of the time on most sites.