Is it right to give people compliments and not ever point out things you don't like about them?

I know compliments make people feel good and criticism makes them feel bad. But isn't it manipulative to flatter their egos to get them to like you/influence them? I want to encourage people and empower them, but I don't want to be manipulative. In the long run, does holding back honest criticism and pouring on praise hurt more than it helps? If it hurts them, yet they like me, isn't that selfish?