YA links are not followed, but they are indirectly valuable for SEO or ranking independently, for 3 reasons:
1) Google interprets the relevant traffic directly to your site as a sign that the site is legitimate, as it is distancing visitors from the search engines. As a result, it classifies it higher and has more natural authority. By contrast, Google treats like many artificial sites that may have hundreds of tracking backlinks, but only a trickle of real traffic.
2) Google also expects that backlinks that are relevant, but not following, are part of the profile of a site with natural authority, while sites that have nothing more than tracking links are seen as artificial, therefore , have a lower classification.
3) Depending on the keyword or niche, the highest classifications for a term may include a YA page. Visitors who click on a YA URL on page 1 of the SEs will likely follow the site link in a YA response to their niche site.