The use of the word buttering implies that we are falsely praising a person. A few people (with very low self esteem) may enjoy being buttered, but others do not.
Consider this. We do not like criticism from anyone – except from those we respect and when we know the persons have a genuine interest in their hearts for me. However, we like praise from anyone. Sometimes, we wish that people notice our work and achievements and talk about it.
So if I am giving positive strokes to my boss for all the good things he has done, or the effort he is putting in, I am simply acknowledging his work. Similarly if I refrain from criticising; and, in fact, support his work with additional data or timely support, then it is not false. I am talking about fetching tea and coffee, polishing his shoes and acting as if he is God, but a genuine appreciation and support goes a long way in creating rapport.
People crave recognition and empathy and providing that makes a person positively predisposed to you. It is not possible to consistently deliver results (due to no fault of ours, but accidents happen) and this positive disposition helps during those times.