The great, glaring gap in just about all ethical systems of which I have knowledge, even when many of the particular values and virtues they advocate may be laudable, is the absence of a technology to assist people in getting there, an effective means for acquiring these values and virtues, a realistic path people can follow. That is the great missing step in most religions and philosophies.
You can tell people that it's a virtue to be rational, productive, or just, but, if they have not already arrived at that stage of awareness and development on their own, objectivism does not tell them how to get there. It does tell you you're rotten if you fail to get there.
Rand's failure to provide a "technology" for attaining Objectivist moral values is not her only failure in this regard. She provided very little in terms of achieving any of the things she regarded as desirable, whether it was rationality, persuasion, or laissez-faire capitalism. And on few occasions where she provided at least the outlines of a technology (as in aesthetics and "philosophical-detection"), what she actually gives us is deeply flawed. Hence the ironic spectacle of Rand followers who don't know how to be rational, Objectivists who don't know how to solve moral conflicts with other Objectivists, and the lack of a strong, vibrant Objectivist artistic movement.