Regarding to the new rules of forum about ranking. I concern someone will trade merit on another website by many ways.
How to detect and prevent that?
Might be it will be increased to 5 if it still do not solve the spam problem. Forum rules has provision to ban user for spamming, might be in next phase many people will be banned for spamming.
Do not worry about other as you cannot control them, just focus on yourself what you can do without breaking any rules and ethics.