The characteristics of the classical Zoom Authority risked to penalize those sites operating in small market niches, blocked to ZA values inevitably lower than the general sites: dealing with less searched topics, with low-volume keywords and naturally lower traffic than online giants, these sites could not emerge beyond a given ZA threshold.
Now, a site about fishing can have a ZA 32 but a TZA equal to 100 or 90 for the specific topic, as the best fishing site in the UK. And this applies to every area of activity.