I think we should create a list of question related to cryptocurrency and new member need to provide right answer for at least 2 or 3 questions if they want to create a new account in here.
The answers to all the questions would quickly appear on Twitter and YouTube, so I'm afraid I fail to see how this suggestion would prevent people from signing up multiple accounts.
Questions aren't an effective way of doing it as they are easily answered and automated and no one wants to go researching complicated questions when they are new to a community.
The only way you would prevent the current situation would be limiting logins. But then the bots would out way the amount of real people that are trying to sign up and would hinder the actual users.
I don't know what can be done other than removing signatures and banning bounties. Thats the only real solution which would prevent 90% of our problems. Yes there will still be spam that not to the degree which it is currently. Lets be honest signature campaigns have ruined the community. I don't really blame users wanting to earn money but at least put some effort into your "job".
But how if moderators give different random questions for each new member and the list of registration questions will be changed every month or week. I think it can help although just a little bit.