While DA is important, I've seen more a correlation with DA and backlinks than I have DA and SEO. I have a site that I've increased the overall SEO by leaps and bounds, removing about 1,000 pages of junk products and useless content pages that could easily been merged into epic category content pages.
I mean I overhauled this site to the T. What did I see in the process? A loss in DA by about 15 points, in the end the culprit? Backlinks, in that time we had the EPA.gov remove a backlink while they redesigned the page themselves, as well lost a few other backlinks from directories that bit the dust and articles that either were removed or some other issue that resulted in backlink loss. Mind you, the SEO and even organic traffic increased in this time period alongside conversation rates.
I think DA might be going the same way pagerank went, since in SEO, there isn't one or even 2 issues that spell success, it's over 9,000.
I also feel, rankbrain will continue to make fools out of us all in the coming years, as it learns and enacts new practices through better optimization and user query intake.