A compliment becomes smaller when it requires an insult to someone else.

Praise that requires putting someone else down is not really praise, it is a comparison with you as the instrument. It also tells the person hearing it exactly how they will be spoken about when they are not in the room, which undercuts whatever warmth the compliment was carrying.

When you want to say something good about someone, say it on its own terms without a foil. Notice how often the reflex to add a contrast appears, and drop it. The compliment lands better, and you have not quietly told the listener that your approval is a ranking.