While Domain Authority is a highly valuable metric that can give you insight as to where you are relative to competitors, it's not necessarily a good KPI to focus on for a number of reasons:
Ddomain authority is based on an exponential function, meaning it's easier to raise your DA from 1 to 2 than it is from 49 to 50. A focus on DA can create frustration if the metric doesn't move, even if everything you're doing is positively impacting rankings, traffic, and conversions.
Relatedly, chasing DA may lead to making bad decisions when it comes to link acquisition. Not all links are made equal and not all high authority links are good. Trying to manipulate your link profile by buying links, for example, can lead to a Google penalty.
Too much emphasis on DA can distract from where your focus should be, which is on the consumer. It can distract from the customer's journey, their needs, and how they are interacting with your website.