Do Web2.0s still work for SEO?

Creating backlinks on good web platform makes your content trustworthy to the search engine, mainly we create backlinks to make contents to be indexed on search engine as Google ,but only Dofollow web authorities allow to get indexed by google.
There are many kinds of backlink activities for off page method as you mentioned about Web 2.0, Also there are article submission, profile backlink, Press release.
In my eyes Web 2.0 is the best plat form to get backlinks because high authority domain and page will boost your page on Search engine.
There are many high authority domain sites as WordPress, Blogger that allow us to establish web 2.0 to create our pages with a unique URL Making your presence on these platforms will help you reach a wider audience for your website.

From what I have seen this method still works, but you need to make sure you are using an updated strategy.  Reason I say this is because SEO is ever evolving and using an up to date strategy works fine than using outdated ones.

Creating accounts on Web 2,0 websites and getting links from them counts but not as much as getting a Do-Follow link.

Web 2.0 gives you No-Follow UGC links which doesn't count as much. Get links from .gov websites as they carry heavy weightage. And get links from Microsoft forums like answers.microsoft. That carries huge advantage as well.