Ego suppression. Brothers who want to get ahead have to be willing to take any counsel and follow pointless rules to the letter. Humility is emphasized as an important trait in Witnesses.
Id suppression. Having to remain chaste until marriage requires repressing the libido. Looking at a woman with desire is also adultery, requiring further suppression.
Super-ego suppression. The organization tells you what is right and wrong. You can't take a stand for any personal beliefs because they detract from the unity of the congregation. You can't allow yourself to feel principled emotions like general compassion towards worldly people, or an obligation to contribute to society, and within the congregation, works are emphasized over showing love to fellow members.
In a nutshell, the religion hollows you out from the inside. How could the men in the congregation not be insipid while also being good Witnesses?