You think crypto casinos are advertising here, because currently bitcointalk members are mostly interested in gambling accordind to you? But how many people are real gamblers on Bitcointalk according to you 50%, 5% or 0.5% ? If so much people like gambling here how do you explain we always see the same few members in almost all betting pools?
Due to a fact that not many signature campaign participants who wear signature for advertising a gambling site actually uses that gambling platform, some gambling companies and their signature campaign managers have a platform account username as one of information for application.
Some campaigns distribute their payments directly to participants' accounts on the gambling platform. By this, these participants will have to withdraw signature campaign payments to their own wallets, and in meantime of storing their campaign payments in gambling accounts, they will be exposed more to a company products. It increases probability that campaign participants will use their payments for gambling too.
I agree with you that very little forum members and gambling signature campaign participants actually gamble.