Not sure about twitters policies regarding this matter but am certain Facebook does not allow referral links and will not allow you to post the same comment or post multiple times. In my opinion, promoting your referral links on social media platforms doesn't seem like a good idea and will be just a waste of time.
If you want active referrals then better promote your links on gambling related blogs and forums and if possible, start your own review website.
I agree with you that posting casino referral links randomly on social media is in many cases not allowed and will not bring many active users. The idea behind referral links is bring your friends into gambling and having a chance to participate of their profits to the casino. I would never use a random referral link if I don't know the person or if he didn't do anything for it. Like making a review of the casino, or making a video about a new gambling strategy. In my opinion you will only find active gamblers willing to use your code if the have been interested in the subject before and if you provide some form of services for them, even if it just summarising some gambling news. Creating a new website for gambling is hard work and will require a lot of time, it might be easier to first work on existing platforms.