It's not a "ploy". Preventing people from promoting their presence on other platforms is the literal stated purpose of the policy. Clearly someone who agrees with the policy would not label that "a place of bad intentions". So if you were to argue with them charitably, you would have to understand why they think it's not bad and convince them that it is bad, not just state it. Of course I agree with you, and I think there are plenty of good arguments to be made! But starting off accusing people of having bad intentions is counterproductive if you want to convince them.