It wouldn't be done if it didn't produce some advantage. The paradigm is the sheep from Orwell's Animal Farm who are taught to bleat, "Two legs bad. Four legs good." over and over again. It may not be intellectually honest or respectable, but there are many people out there who buy into it.
Monitor: Airstrikes hit Islamic State stronghold in Syria, killing at least 13 (Reuters)
from the article: Fear and exclusion of J Street is misguided and destructive