Some people want to resort to them to measure the quality of their site and/or site ranking power. OK, in the past, the big one was Google PR - but now it is either gone or made secret.
Anyway, here is the jist of the topic. Basically, you don't want to trust domain authority alone (DA). Instead, it's better to look at it - along with other ones (trust flow, trust metric). Why do I say that? Well, a high domain authority along with poorer scores in other metrics can indicate spam - basically a false high quality.