Bitcointalk signatures are nofollow, which means they are useless for SEO
Only do-follow links help with SEO because they tell the search engine to process the website being referred to in the link, which can boost SEO. However, sig campaigns, and by extension all Bitcointalk signatures, do not benefit from this, because do-follow is turned off by the administrator/forum software to prevent spam from being promoted via Bitcointalk.
That's not entirely true with due respect NotATether, signatures do have ranking factor.
Ok first of all if you inspect the signature links you will find it is
rel="ugc" UGC, not nofollow. UGC is bit different than nofollow
The UGC link attribute (rel=“UGC”) is an attribute that signals to Google that the link is placed in user-generated content. This attribute was introduced in 2019 when Google changed how the “nofollow” attribute works.
The UGC attribute doesn’t have a significant impact on a website’s SEO rank. But, it is recommended to use this attribute on any links in the content written by your website visitors. This can include comments, reviews, and other types of user-submitted content.
adding the UGC attribute is a good practice to ensure your site doesn’t get penalized for having unnatural external links. This is because comment links are usually spammy links associated with black hat SEO.
This applies to "links" only in the signature which is to avoid main site "bitcointalk.org" to avoid getting penalized for any spammy links.
However other content in the signature which includes Project Names, Website Title or any other links twitter, telegram etc must have ranking ranking factor in SEO.
In short ugc, user-generated content is a confirmed a ranking factor and google can't differentiate between content of the website and content of the users in this case signature.
Yes the links in the signature will tell a Search Engine that this specific link is "user generated", so don't blame me (bitcointalk) for any spam in this link