Hi, definitely, they have always been valuable, however, the type of backlink matters a lot, ie.: two do-follow links are not always created equal. For example you can get a dofollow link by creating a Web2.0 property, or you can get a dofollow backlink if an authority site from your niche links to you. You can guess that the second one is far more difficult to achieve, and because of this, it's also far more valuable. I have a site in the fitness niche where I have over 300 backlinks of the "second type": I built all those backlinks using white hat outreach link building strategies. If I'm allowed and if anyone case I'd be happy to share my website URL as a case study and go into a little bit more depth about how I got those backlinks and how anyone can replicate my strategies. In the meantime, here is a screenshot of my site's analytics attached.
Yeah obviously do follow links increase ranking if the link comes from some good site and Google also gives importance to do follow links.
Yes. obviously, If you are getting most relevant do follow links from high DA websites then it will definitely give you advantages to improve your ranking in SEO.
There are 2 types of backlink Do Follow and nofollow. According to Google, you have to maintain 60:40 ratio of DoFollow and NoFollow link if not maintain this ratio it may cause your website trouble. Before creating any link from any website, you have to check Domain authority and page authority, and relevancy. DoFollow links are more important because link juice is passed through Dofollow which make a huge impact on your ranking if that come from high PR, DA and PA sites. This is why people want to make so many do-follow links from the high PA and DA website.