First thing to remember: DA is a 3rd party metric that is not in any way affiliated with ANY search engine, and Moz does not have any special insight into Google's algorithm than you or I.
That said, what that is about is that some time ago, Moz started devaluing subdomains of certain (not all) web 2.0s that everyone and their mother had been hammering shamelessly with complete garbage, in a lot of cases building DA solely on those sites
Affected sites are your most commonly built with software (at the time) such as WordPress (.com) , Weebly, wix, webs, hatena, jimdo (their old domain for free sites), blogspot, live journal, over-blog, Tumblr, and about a dozen or so others because Moz believes that links from these subdomains are more likely than not devalued by Google. (This is probably true, but I caveat that statement because again, they are not Google and they can only go by educated guess and speculation, although IMO this one's probably true)
Because this happened around the same time as a particular Twitter interview with John Mueller where he said subdomains are sometimes (mealry mouthed Mueller), treated as separate domains,
a lot of people think that Moz devalues all subdomains across the board to DA 1, but this is. Not at all true.
examples of complely unaffected high DA web 2.0s Include jimdo (their newer domain for free sites) all of WordPress.com's ".blog" domains(home.blog subdomains are DA 91 PA 41), telegra.ph (subdirectory), pagexl, webador, my strikingly, puzl, website.com (website2.me) and any of literally hundreds if not thousands of others.
If you are looking specifically for Web 2.0 with the vanity numbers of appearing higher da and PA, there are still thousands of options available to you, but IMO Google most likely is well aware of all of these being exactly what they are and probably treats them absolutely no differently than they do any wordpress.com website
So, if you're looking to these types of easy links to improve your actual search rankings and get you actual traffic, you're going to be sorely disappointed no matter which one you use, unless of course you treat it as a parasite SEO property and pump it up with tons of backlinks to power It up in order to pass on a bunch of link juice to you., And of course you would need to post some content on there that is at least halfway decent and would provide some value to someone in
On the other hand, if you are just looking to improve your da to boost your morale or make your site look better or as though it has a more robust variety of sites linking to you, this approach might work for you.