They probably do to some extent, directly or indirectly. If nothing else, there are probably diminishing returns to building increasingly more web 2.0 backlinks from the same root/parent domain.
As to why they don't completely devalue web 2.0 backlinks, you could as the same of any link type. Backlinks are easy to get through all of these methods:
- Free guest post sites
- Paid guest post sites
- Reddit backlinks
- Voat (lmao) backlinks
- Quora backlinks
- Youtube video backlinks
- Basically every social media site's backlinks
- PBNs
- Blog comments, forum comments, profile links, etc
- Scholarship links
- Donor links
- And so on and so forth
While the users of BHW might forget it, there are real users on sites like Weebly, Wordpress, and Tumblr. And when those users make real posts that "go viral" (or whatever the kids say these days) and get backlinks (both internal and external), that is a real, useful signal to Google of content quality. At the end of the day, the most likely answer as to why they haven't devalued these is because if they devalued everything that was exploitable, there would be basically no data for them to rank sites off of at all.
In theory, Google takes that information in the larger context of a site's full backlink profile, on page optimization, etc. and bases those rankings off of a number of factors and
in theory aims to avoid giving too much weight to any one domain's backlinks or any one backlink type.
they did put an outbound link penalty to sites like ezinearticles.
As in Google was penalizing for backlinks from eZinearticles to money sites? I can't seem to find anything indicating that this was the case. The did change their links to nofollow in 2014, according to this article, but haven't found anything else on the subject:
https://blog.ezinearticles.com/2014/09/ezinearticles-com-links-are-now-100-percent-nofollow.html
