I would agree in many cases this is very true. An alcoholic should be told to quit drinking; the person who hogs all the discussion in a Bible study should be told to listen once in a while, etc etc. There are thousands of situations where we should not spare a person's feelings by being untruthful.A person should not lie to save someone's feelings.
But there are also many situations where, out of love, it is not wrong to tell an untruth. In our ongoing example, what good would it serve to tell my dear mother that her dinner was awful? She'd be upset and I'd be upset, and it would not change the fact that the dinner was awful.
One more quick observation: We must be careful that "speaking the truth in love" is not simply a tactic to make ourselves feel better about ourselves.
"Criticism serves to make you harsh, vindictive, and cruel, and leaves you with the soothing and flattering idea that you are somehow superior to others. Jesus says that as His disciple you should cultivate a temperament that is never critical. This will not happen quickly but must be developed over a span of time. You must constantly beware of anything that causes you to think of yourself as a superior person." ~~Oswald Chambers