I wonder what their end goal is... somehow converting those users (or readers, if there are any) to yobit users?
Yeah, I can't figure that out either.
May be I am completely wrong but this is what I assume the main reason behind the astonishing campaigning from Yobit merely for a forum: Yobit conducts IEO (ICO) once or so every month. Currently Yobit intimates users about these through email. But to increase the success of these ICOs, YoBit needs higher community participation. Due to bad reputation on Bitcointalk, it is hard for YoBit to announce IEOs on Bitcointalk. Hence they developed Cryptotalk as an asset to increase participation in coin funding and to catalyst their pump/dump operations.
Spammers are usually short of money and therefore they can't invest in Yobit ICO. If there are no decent people on their forum, there is no way they can gain investors from their own forum.